Silence compiler warnings when building with Clang or new engine headers

Utils.h

@@ -152,9 +152,9 @@ void UI_FreeCustomStrings( void );
 
 inline size_t Q_strncpy( char *dst, const char *src, size_t size )
 {
-	register char	*d = dst;
-	register const char	*s = src;
-	register size_t	n = size;
+	char	*d = dst;
+	const char	*s = src;
+	size_t	n = size;
 
 	if( !dst || !src || !size )
 		return 0;

extdll_menu.h

@@ -16,12 +16,19 @@ GNU General Public License for more details.
 #ifndef EXTDLL_H
 #define EXTDLL_H
 
+// includes xash3d_types.h on Xash3D FWGS, which defines EXPORT
+// but harmless on any HLSDK or Xash3D
+#include "const.h"
+
+#ifndef EXPORT
 #ifdef _WIN32
 #define EXPORT __declspec(dllexport)
+#elif defined(__GNUC__)
+#define EXPORT __attribute__((visibility("default")))
 #else
 #define EXPORT
 #endif
-
+#endif
 
 // shut-up compiler warnings
 #ifdef _MSC_VER