improve z copy a little further in 4 bits copy,

fix and error introduced by my last commit in dx11 plugin

git-svn-id: https://dolphin-emu.googlecode.com/svn/trunk@6754 8ced0084-cf51-0410-be5f-012b33b47a6e

Source/Core/VideoCommon/Src/TextureCacheBase.cpp

@@ -469,6 +469,7 @@ void TextureCache::CopyRenderTargetToTexture(u32 address, bool bFromZBuffer,
 			{
 			case 0: // Z4				
 				colmat[3] = colmat[7] = colmat[11] = colmat[15] = 1;
+				cbufid = 20;
 				break;
 			case 1: // Z8
 			case 8: // Z8