Restrict uniform array flattening to sampler and texture arrays.

Previously the uniform array flattening feature would trigger on loose
uniform arrays of any basic type (e.g, floats).  This PR restricts it
to sampler and texture arrays.  Other arrays would end up in their own
uniform block (anonymous or otherwise).  (Atomic counter arrays might be an
exception, but those are not currently flattened).

hlsl/hlslParseHelper.cpp

@@ -736,7 +736,9 @@ bool HlslParseContext::shouldFlattenUniform(const TType& type) const
 
     return type.isArray() &&
         intermediate.getFlattenUniformArrays() &&
-        qualifier == EvqUniform;
+        qualifier == EvqUniform &&
+        // Testing the EbtSampler basic type covers samplers and textures
+        type.getBasicType() == EbtSampler;
 }
 
 void HlslParseContext::flatten(const TSourceLoc& loc, const TVariable& variable)