Revert of added support for push_constant layout

tests/SkSLErrorTest.cpp

 /*
  * Copyright 2016 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #include "SkSLCompiler.h"
 
 #include "Test.h"
 
-#if SK_SUPPORT_GPU
+#if SKIA_SUPPORT_GPU
 
 static void test_failure(skiatest::Reporter* r, const char* src, const char* error) {
     SkSL::Compiler compiler;
     std::stringstream out;
     bool result = compiler.toSPIRV(SkSL::Program::kFragment_Kind, src, out);
     if (compiler.errorText() != error) {
         SkDebugf("SKSL ERROR:\n    source: %s\n    expected: %s    received: %s", src, error,
                  compiler.errorText().c_str());
     }
     REPORTER_ASSERT(r, !result);
@@ skipping 342 matching lines @@
                  "error: 1: unknown identifier 'x'\n1 error\n");
     test_failure(r,
                  "void foo() { true ? 5 : x; }",
                  "error: 1: unknown identifier 'x'\n1 error\n");
     test_failure(r,
                  "void foo() { false ? x : 5; }",
                  "error: 1: unknown identifier 'x'\n1 error\n");
 }
 
 #endif