This fixes a number of things that are warnings in the Mac compiler....

core/cross/gl/primitive_gl.cc

 /*
  * Copyright 2009, Google Inc.
  * All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions are
  * met:
  *
  *     * Redistributions of source code must retain the above copyright
  * notice, this list of conditions and the following disclaimer.
@@ skipping 232 matching lines @@
       gl_primitive_type = GL_TRIANGLE_FAN;
       break;
     }
     default : {
       DLOG(ERROR) << "Unknown Primitive Type in Primitive: "
                   << primitive_type_;
       draw = false;
     }
   }
   if (draw) {
-    DCHECK_NE(gl_primitive_type, GL_NONE);
+    DCHECK_NE(gl_primitive_type, static_cast<unsigned int>(GL_NONE));
     renderer->AddPrimitivesRendered(number_primitives_);
     if (indexed())
       glDrawElements(gl_primitive_type,
                      index_count,
                      GL_UNSIGNED_INT,
                      BUFFER_OFFSET(start_index() * sizeof(uint32)));  // NOLINT
     else
       glDrawArrays(gl_primitive_type, start_index(), index_count);
   }
 
   // Clean up the shaders.
   effect_gl->PostDraw(param_cache_gl);
 
   // Disable the vertex attribute states set earlier.
   for (ParamCacheGL::VaryingParameterMap::iterator i = varying_map.begin();
        i != varying_map.end();
        ++i) {
     cgGLDisableClientState(i->first);
   }
   CHECK_GL_ERROR();
 }
 
 }  // namespace o3d