Fix remaining issues on PPC64EL

One AltiVec-related build issue remained
Self tests now pass on LE POWER platforms

Signed-off-by: Timothy Pearson <tpearson@raptorengineering.com>

src/nvtt/squish/maths.h

@@ -26,10 +26,18 @@
 #ifndef NV_SQUISH_MATHS_H
 #define NV_SQUISH_MATHS_H
 
+#if NV_USE_ALTIVEC
+#undef vector
+#endif
+
 #include <cmath>
 #include <algorithm>
 #include "config.h"
 
+#if NV_USE_ALTIVEC
+#define vector __vector
+#endif
+
 namespace nvsquish {
 
 class Vec3