elfutils cc1: all warnings being treated as errors

/**********************************************************************
 *         elfutils cc1: all warnings being treated as errors
 * 说明：
 *     在Ubuntu 18.04上编译Yocto，elfutils的Makefile中出现没有识别到一些配置，
 * 需要在Makefile中去掉-Werror选项。
 *
 *                                2018-6-14 深圳 宝安西乡 曾剑锋
 *********************************************************************/

一、参考文档：
    . How to compile without warnings being treated as errors?
        https://stackoverflow.com/questions/11561261/how-to-compile-without-warnings-being-treated-as-errors
    . all warnings being treated as errors
        https://wizardforcel.gitbooks.io/100-gcc-tips/content/warnings-treated-as-errors.html

二、报错现象：
    . 现象：
        x86_64-linux/usr/include -O2 -pipe -c -o dwfl_report_elf.o ../../elfutils-0.164/libdwfl/dwfl_report_elf.c
        | ../../elfutils-0.164/libdwfl/dwfl_report_elf.c: In function '__libdwfl_elf_address_range':
        | ../../elfutils-0.164/libdwfl/dwfl_report_elf.c::: error: this statement may fall through [-Werror=implicit-fallthrough=]
        |        add_p_vaddr = true;
        |                    ^
        | ../../elfutils-0.164/libdwfl/dwfl_report_elf.c::: note: here
        |      case ET_DYN:
        |      ^~~~
        | cc1: all warnings being treated as errors
        | Makefile:: recipe for target 'dwfl_report_elf.o' failed
    . 现象：
        imx6q-x11/tmp/sysroots/x86_64-linux/usr/include -O2 -pipe -c -o dwarf_next_cfi.o ../../elfutils-0.164/libdw/dwarf_next_cfi.c
        | In file included from ../../elfutils-0.164/libdw/dwarf_next_cfi.c:::
        | ../../elfutils-0.164/libdw/encoded-value.h: In function 'encoded_value_size':
        | ../../elfutils-0.164/libdw/encoded-value.h::: error: this statement may fall through [-Werror=implicit-fallthrough=]
        |        if (p != NULL)
        |           ^
        | ../../elfutils-0.164/libdw/encoded-value.h::: note: here
        |      default:
        |      ^~~~~~~
        | cc1: all warnings being treated as errors
        | Makefile:: recipe for target 'dwarf_next_cfi.o' failed
        | make[]: *** [dwarf_next_cfi.o] Error
    . 现象：
        inux/usr/include -O2 -pipe -c -o i386_disasm.o ../../elfutils-0.164/libcpu/i386_disasm.c
        | ../../elfutils-0.164/libcpu/i386_disasm.c: In function 'i386_disasm':
        | ../../elfutils-0.164/libcpu/i386_disasm.c::: error: this statement may fall through [-Werror=implicit-fallthrough=]
        |       if (data[] == 0xc2)
        |          ^
        | ../../elfutils-0.164/libcpu/i386_disasm.c::: note: here
        |     default:
        |     ^~~~~~~
        | cc1: all warnings being treated as errors
        | Makefile:: recipe for target 'i386_disasm.o' failed

三、解决方法：
    . 原因： cc1: all warnings being treated as errors
    . 修改对应的Makefile，去掉-Werror：
    . 手动处理示例：
        /home/zengjf/zengjf/fsl-release-bsp/imx6q-x11/tmp/work/x86_64-linux/elfutils-native/0.164-r0/build/libdwfl/Makefile
            [...省略]
            # Warn about stack usage of more than 256K =  bytes.
            STACK_USAGE_WARNING = -Wstack-usage=
            AM_CFLAGS = -std=gnu99 -Wall -Wshadow -Wformat= \
                        -Wold-style-definition -Wstrict-prototypes \
                        $(if $($(*F)_no_Werror),,-Werror) \                         # remove this line
                        $(if $($(*F)_no_Wunused),,-Wunused -Wextra) \
                        $(if $($(*F)_no_Wstack_usage),,$(STACK_USAGE_WARNING)) \
                        $($(*F)_CFLAGS)
            [...省略]
    . 获取Makefile生成信息：
        zengjf@zengjf:~/zengjf/fsl-release-bsp/imx6q-x11/tmp/work/x86_64-linux/elfutils-native/0.164-r0$ grep _no_Werror * -r
        build/tests/Makefile:        $(if $($(*F)_no_Werror),,-Werror) \
        build/libdwfl/Makefile.bak:        $(if $($(*F)_no_Werror),,-Werror) \
        build/backends/Makefile:        $(if $($(*F)_no_Werror),,-Werror) \
        build/libdwelf/Makefile:        $(if $($(*F)_no_Werror),,-Werror) \
        build/lib/Makefile:    $($(*F)_no_Werror),,-Werror) $(if \
        build/libasm/Makefile:        $(if $($(*F)_no_Werror),,-Werror) \
        build/libelf/Makefile:    $($(*F)_no_Werror),,-Werror) $(if \
        build/libebl/Makefile:    $($(*F)_no_Werror),,-Werror) $(if \
        build/src/Makefile:        $(if $($(*F)_no_Werror),,-Werror) \
        build/src/Makefile:ldlex_no_Werror = yes
        build/libcpu/Makefile:i386_lex_no_Werror = yes
        elfutils-0.164/tests/Makefile.in:        $(if $($(*F)_no_Werror),,-Werror) \
        elfutils-0.164/libdwfl/Makefile.in:        $(if $($(*F)_no_Werror),,-Werror) \
        elfutils-0.164/backends/Makefile.in:        $(if $($(*F)_no_Werror),,-Werror) \
        elfutils-0.164/config/eu.am:        $(if $($(*F)_no_Werror),,-Werror) \
        elfutils-0.164/libdwelf/Makefile.in:        $(if $($(*F)_no_Werror),,-Werror) \
        elfutils-0.164/libdw/Makefile.in:    $($(*F)_no_Werror),,-Werror) $(if \
        elfutils-0.164/lib/Makefile.in:    $($(*F)_no_Werror),,-Werror) $(if \
        elfutils-0.164/libasm/Makefile.in:        $(if $($(*F)_no_Werror),,-Werror) \
        elfutils-0.164/libelf/Makefile.in:    $($(*F)_no_Werror),,-Werror) $(if \
        elfutils-0.164/libebl/Makefile.in:    $($(*F)_no_Werror),,-Werror) $(if \
        elfutils-0.164/src/Makefile.in:        $(if $($(*F)_no_Werror),,-Werror) \
        elfutils-0.164/src/Makefile.in:ldlex_no_Werror = yes
        elfutils-0.164/src/Makefile.am:ldlex_no_Werror = yes
        elfutils-0.164/libcpu/Makefile.in:    $($(*F)_no_Werror),,-Werror) $(if \
        elfutils-0.164/libcpu/Makefile.in:i386_lex_no_Werror = yes
        elfutils-0.164/libcpu/Makefile.am:i386_lex_no_Werror = yes
        elfutils-0.164/.pc/dso-link-change.patch/src/Makefile.am:ldlex_no_Werror = yes
        elfutils-0.164/.pc/uclibc-support.patch/libcpu/Makefile.am:i386_lex_no_Werror = yes
        zengjf@zengjf:~/zengjf/fsl-release-bsp/imx6q-x11/tmp/work/x86_64-linux/elfutils-native/0.164-r0$
    . 一个一个文件修改比较麻烦，依据第4点，修改对应的yes为no就可以比较快捷的一次性全部解决问题，然而实际情况是没有识别到ldlex和i386_lex，乖乖的手动删除或者制作Shell脚本处理；
    . 自动化shell命令：
        . grep _no_Werror\) * -r | cut -d":" -f1 | xargs sed -i "s/[$](if [$]([$]([*F]*)_no_Werror),,-Werror)//"
        . grep _no_Werror\) * -r | cut -d":" -f1 | xargs sed -i "s/[$]([$]([*F]*)_no_Werror),,-Werror) [$](if//"