stb_sprintf: PUBLICDEC on declarations, as intended

The code was using PUBLICDEF on both declarations and
definitions.

Fixes issue #458.

stb_sprintf.h

@@ -199,13 +199,13 @@ typedef char *STBSP_SPRINTFCB(const char *buf, void *user, int len);
 #define STB_SPRINTF_DECORATE(name) stbsp_##name // define this before including if you want to change the names
 #endif
 
-STBSP__PUBLICDEF int STB_SPRINTF_DECORATE(vsprintf)(char *buf, char const *fmt, va_list va);
-STBSP__PUBLICDEF int STB_SPRINTF_DECORATE(vsnprintf)(char *buf, int count, char const *fmt, va_list va);
-STBSP__PUBLICDEF int STB_SPRINTF_DECORATE(sprintf)(char *buf, char const *fmt, ...) STBSP__ATTRIBUTE_FORMAT(2,3);
-STBSP__PUBLICDEF int STB_SPRINTF_DECORATE(snprintf)(char *buf, int count, char const *fmt, ...) STBSP__ATTRIBUTE_FORMAT(3,4);
+STBSP__PUBLICDEC int STB_SPRINTF_DECORATE(vsprintf)(char *buf, char const *fmt, va_list va);
+STBSP__PUBLICDEC int STB_SPRINTF_DECORATE(vsnprintf)(char *buf, int count, char const *fmt, va_list va);
+STBSP__PUBLICDEC int STB_SPRINTF_DECORATE(sprintf)(char *buf, char const *fmt, ...) STBSP__ATTRIBUTE_FORMAT(2,3);
+STBSP__PUBLICDEC int STB_SPRINTF_DECORATE(snprintf)(char *buf, int count, char const *fmt, ...) STBSP__ATTRIBUTE_FORMAT(3,4);
 
-STBSP__PUBLICDEF int STB_SPRINTF_DECORATE(vsprintfcb)(STBSP_SPRINTFCB *callback, void *user, char *buf, char const *fmt, va_list va);
-STBSP__PUBLICDEF void STB_SPRINTF_DECORATE(set_separators)(char comma, char period);
+STBSP__PUBLICDEC int STB_SPRINTF_DECORATE(vsprintfcb)(STBSP_SPRINTFCB *callback, void *user, char *buf, char const *fmt, va_list va);
+STBSP__PUBLICDEC void STB_SPRINTF_DECORATE(set_separators)(char comma, char period);
 
 #endif // STB_SPRINTF_H_INCLUDE