Fix build problems under OS X

code/renderer/tr_shade.c

@@ -21,8 +21,8 @@ Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
 */
 // tr_shade.c
 
-#include "tr_local.h"
-#if idppc_altivec
+#include "tr_local.h" 
+#if idppc_altivec && !defined(MACOS_X)
 #include <altivec.h>
 #endif
 

code/renderer/tr_shade_calc.c

@@ -22,7 +22,7 @@ Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
 // tr_shade_calc.c
 
 #include "tr_local.h"
-#if idppc_altivec
+#if idppc_altivec && !defined(MACOS_X)
 #include <altivec.h>
 #endif
 

code/renderer/tr_surface.c

@@ -21,7 +21,7 @@ Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
 */
 // tr_surf.c
 #include "tr_local.h"
-#if idppc_altivec
+#if idppc_altivec && !defined(MACOS_X)
 #include <altivec.h>
 #endif