Check for weakly linked OpenCL.

git-svn-id: https://dolphin-emu.googlecode.com/svn/trunk@5811 8ced0084-cf51-0410-be5f-012b33b47a6e

Source/Core/Common/Src/OpenCL.cpp

@@ -51,6 +51,9 @@ bool Initialize()
 	if(!clrHasOpenCL())
 		return false;
 #endif
+	// If OpenCL is weakly linked and not found, its symbols will be NULL
+	if (clGetPlatformIDs == NULL)
+		return false;
 
 	// Connect to a compute device
 	cl_uint numPlatforms;