Move cpp includes out of extern "C" block

Author: z2oh

extensions/include/cmark-gfm-core-extensions.h

@@ -1,16 +1,17 @@
 #ifndef CMARK_GFM_CORE_EXTENSIONS_H
 #define CMARK_GFM_CORE_EXTENSIONS_H
 
+#include "cmark-gfm-extension_api.h"
+
+#include <stdbool.h>
+#include <stdint.h>
+
 #ifdef __cplusplus
 extern "C" {
 #endif
 
-#include "cmark-gfm-extension_api.h"
 #include "export.h"
 
-#include <stdbool.h>
-#include <stdint.h>
-
 CMARK_GFM_EXPORT
 void cmark_gfm_core_extensions_ensure_registered(void);