Fix unrefenced variable warning with AMD_EXTENSIONS disabled.

SPIRV/GlslangToSpv.cpp

@@ -4118,11 +4118,9 @@ spv::Id TGlslangToSpvTraverser::createAtomicOperation(glslang::TOperator op, spv
 // Create group invocation operations.
 spv::Id TGlslangToSpvTraverser::createInvocationsOperation(glslang::TOperator op, spv::Id typeId, std::vector<spv::Id>& operands, glslang::TBasicType typeProxy)
 {
-    bool isUnsigned = typeProxy == glslang::EbtUint || typeProxy == glslang::EbtUint64;
 #ifdef AMD_EXTENSIONS
+    bool isUnsigned = typeProxy == glslang::EbtUint || typeProxy == glslang::EbtUint64;
     bool isFloat = typeProxy == glslang::EbtFloat || typeProxy == glslang::EbtDouble || typeProxy == glslang::EbtFloat16;
-#else
-    bool isFloat = typeProxy == glslang::EbtFloat || typeProxy == glslang::EbtDouble;
 #endif
 
     spv::Op opCode = spv::OpNop;