HLSL: allow name mangling based on texture template type

Name mangling did not account for the vector size in the template type of a texture.
This adds that.  The mangle is as it ever was for the vec4 case, which leaves
all GLSL behavior and most HLSL behavior uneffected.  For vec1-3 the size is added
to the mangle.

Current limitation: textures cannot presently be templatized on structured types,
so this works only for vectors of basic types.

Fixes #895.

glslang/MachineIndependent/SymbolTable.cpp

@@ -99,6 +99,14 @@ void TType::buildMangledName(TString& mangledName) const
         case EsdSubpass:  mangledName += "P";  break;
         default: break; // some compilers want this
         }
+
+        switch (sampler.vectorSize) {
+        case 1: mangledName += "1"; break;
+        case 2: mangledName += "2"; break;
+        case 3: mangledName += "3"; break;
+        case 4: break; // default to prior name mangle behavior
+        }
+
         if (sampler.ms)
             mangledName += "M";
         break;