Fix mat2 packing to use 2 rows as per spec.

git-svn-id: https://angleproject.googlecode.com/svn/branches/dx11proto@1815 736b8ea6-26fd-11df-bfd4-992fa37f6226
diff --git a/src/compiler/VariablePacker.cpp b/src/compiler/VariablePacker.cpp
index 2f0c4bc..8957287 100644
--- a/src/compiler/VariablePacker.cpp
+++ b/src/compiler/VariablePacker.cpp
@@ -85,7 +85,7 @@
         case SH_FLOAT_MAT3:
             return 3;
         case SH_FLOAT_MAT2:
-            return 1;
+            return 2;
         case SH_FLOAT_VEC4:
         case SH_INT_VEC4:
         case SH_BOOL_VEC4: