strerror_override: re-organize strerror_override.h

Always include <string.h> before _json_c_strerror() definition.
Should fix linker issues on MSVC.

Signed-off-by: Alexandru Ardelean <ardeleanalex@gmail.com>

strerror_override.h

@@ -10,12 +10,12 @@
 extern "C" {
 #endif
 
+#include <string.h>
+
 JSON_EXPORT char *_json_c_strerror(int errno_in);
 
 #ifndef STRERROR_OVERRIDE_IMPL
 #define strerror	_json_c_strerror
-#else
-#include <string.h>
 #endif
 
 #ifdef __cplusplus