libretro-common : fix extern C guards in encodings/utf.h

desmume/src/libretro-common/include/encodings/utf.h

@@ -23,11 +23,15 @@
 #ifndef _LIBRETRO_ENCODINGS_UTF_H
 #define _LIBRETRO_ENCODINGS_UTF_H
 
+#include <retro_common_api.h>
+
 #include <stdint.h>
 #include <stddef.h>
 
 #include <boolean.h>
 
+RETRO_BEGIN_DECLS
+
 size_t utf8_conv_utf32(uint32_t *out, size_t out_chars,
       const char *in, size_t in_size);
 
@@ -40,4 +44,6 @@ size_t utf8cpy(char *d, size_t d_len, const char *s, size_t chars);
 
 const char *utf8skip(const char *str, size_t chars);
 
+RETRO_END_DECLS
+
 #endif