编译freetype 的dll

因需要给python使用freetype库，so需要一个freetype的dll

2 steps

1. 在VC中设置输出为动态链接库

2. 修改ftoption.h

在284行增加2行代码即可

  /*************************************************************************/
  /*                                                                       */
  /* DLL export compilation                                                */
  /*                                                                       */
  /*   When compiling FreeType as a DLL, some systems/compilers need a     */
  /*   special keyword in front OR after the return type of function       */
  /*   declarations.                                                       */
  /*                                                                       */
  /*   Two macros are used within the FreeType source code to define       */
  /*   exported library functions: FT_EXPORT and FT_EXPORT_DEF.            */
  /*                                                                       */
  /*     FT_EXPORT( return_type )                                          */
  /*                                                                       */
  /*       is used in a function declaration, as in                        */
  /*                                                                       */
  /*         FT_EXPORT( FT_Error )                                         */
  /*         FT_Init_FreeType( FT_Library*  alibrary );                    */
  /*                                                                       */
  /*                                                                       */
  /*     FT_EXPORT_DEF( return_type )                                      */
  /*                                                                       */
  /*       is used in a function definition, as in                         */
  /*                                                                       */
  /*         FT_EXPORT_DEF( FT_Error )                                     */
  /*         FT_Init_FreeType( FT_Library*  alibrary )                     */
  /*         {                                                             */
  /*           ... some code ...                                           */
  /*           return FT_Err_Ok;                                           */
  /*         }                                                             */
  /*                                                                       */
  /*   You can provide your own implementation of FT_EXPORT and            */
  /*   FT_EXPORT_DEF here if you want.  If you leave them undefined, they  */
  /*   will be later automatically defined as `extern return_type' to      */
  /*   allow normal compilation.                                           */
  /*                                                                       */
  /*   Do not #undef these macros here since the build system might define */
  /*   them for certain configurations only.                               */
  /*                                                                       */
/* #define FT_EXPORT(x)      extern x */
/* #define FT_EXPORT_DEF(x)  x */
#define FT_EXPORT(x) __declspec(dllexport) x
#define FT_BASE(x) __declspec(dllexport) x

另外，生成的dll直接放入phthon.exe所在目录即可，无需放入system32下。