Rename CHAR_WIDTH to CHARACTER_WIDTH

For some time glibc has defined a macro with the same name in limits.h.
Avoid the warning by renaming our macro.

code/cgame/cg_local.h

@@ -63,7 +63,7 @@ Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
 #define STAT_MINUS			10	// num frame for '-' stats digit
 
 #define	ICON_SIZE			48
-#define	CHAR_WIDTH			32
+#define	CHARACTER_WIDTH			32
 #define	CHAR_HEIGHT			48
 #define	TEXT_ICON_SPACE		4