include/freetype/internal/compiler-macros.h (FT_CALLBACK_DEF):
don't define as __cdecl for Watcom builds.

Otherwise, conflicts happen with Watcom default calling convention
which is 'watcall'. E.g.:

src/base/ftrfork.c(292): Error! E1071: Type of parameter 4 does not agree with previous definition
src/base/ftrfork.c(292): Note! I2003: source conversion type is 'int (__cdecl *)(void const *__p1,void const *__p2)'
src/base/ftrfork.c(292): Note! I2004: target conversion type is 'int (*)(void const *__p1,void const *__p2)'
src/base/ftrfork.c(292): Note! I2002: 'qsort' defined in: /opt/watcom/h/stdlib.h(213)

diff --git a/include/freetype/internal/compiler-macros.h b/include/freetype/internal/compiler-macros.h
index 88c0bf0..0328a52 100644
--- a/include/freetype/internal/compiler-macros.h
+++ b/include/freetype/internal/compiler-macros.h
@@ -301,7 +301,7 @@ FT_BEGIN_HEADER
 
 #if defined( __i386__ )
 #define FT_COMPARE_DEF( x )  FT_CALLBACK_DEF( x ) __attribute__(( cdecl ))
-#elif defined( _M_IX86 )
+#elif defined( _M_IX86 ) && !defined(__WATCOMC__)
 #define FT_COMPARE_DEF( x )  FT_CALLBACK_DEF( x ) __cdecl
 #else
 #define FT_COMPARE_DEF( x )  FT_CALLBACK_DEF( x )