Shader UID change: Only store the two bits of components we need.

This frees up 21 bits and allows us to shorten the UID struct by an entire
32 bits.

It's not strictly needed (as it's encoded into the length) but I added a
bit for per-pixel lighiting to make my life easier in the following
commits.

Source/Core/VideoCommon/NativeVertexFormat.h

@@ -31,6 +31,7 @@ enum
   VB_HAS_NRM2 = (1 << 12),
   VB_HAS_NRMALL = (7 << 10),
 
+  VB_COL_SHIFT = 13,
   VB_HAS_COL0 = (1 << 13),
   VB_HAS_COL1 = (1 << 14),