Merge pull request #602 from ReliaSolve/mac_build_improvements

Builds out of the box on mac with ASSIMP_BUILD_SAMPLES turned on.

samples/SimpleOpenGL/Sample_SimpleOpenGL.c

@@ -14,7 +14,11 @@
 #include <stdlib.h>
 #include <stdio.h>
 
+#ifdef __APPLE__
+#include <glut.h>
+#else
 #include <GL/glut.h>
+#endif
 
 /* assimp include files. These three are usually needed. */
 #include <assimp/cimport.h>