Reland "SkSL CPP and H backends no longer emitted in non-dev builds"

This is a reland of bc6fb279fe9714947ecd1fadcff22ef84785c349

Original change's description:
> SkSL CPP and H backends no longer emitted in non-dev builds
> 
> As these backends are never used at runtime, it's pointless to include
> them in the Skia binaries. We still include them in GR_TEST_UTILS mode
> to support unit tests.
> 
> Change-Id: I9ec9cc9300b74c501985656323ec894008255a70
> Reviewed-on: https://skia-review.googlesource.com/c/skia/+/311454
> Commit-Queue: Brian Osman <brianosman@google.com>
> Reviewed-by: John Stiles <johnstiles@google.com>
> Reviewed-by: Brian Osman <brianosman@google.com>

Change-Id: I214d6d952befbe77f301cf252fe4795f8c411a76
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/312242
Reviewed-by: Ethan Nicholas <ethannicholas@google.com>
Commit-Queue: Ethan Nicholas <ethannicholas@google.com>
diff --git a/src/sksl/SkSLCompiler.cpp b/src/sksl/SkSLCompiler.cpp
index 543dfed..9795a1e 100644
--- a/src/sksl/SkSLCompiler.cpp
+++ b/src/sksl/SkSLCompiler.cpp
@@ -1771,6 +1771,7 @@
     return result;
 }
 
+#if defined(SKSL_STANDALONE) || defined(GR_TEST_UTILS)
 bool Compiler::toCPP(Program& program, String name, OutputStream& out) {
     if (!this->optimize(program)) {
         return false;
@@ -1792,8 +1793,9 @@
     fSource = nullptr;
     return result;
 }
+#endif // defined(SKSL_STANDALONE) || defined(GR_TEST_UTILS)
 
-#endif
+#endif // defined(SKSL_STANDALONE) || SK_SUPPORT_GPU
 
 #if !defined(SKSL_STANDALONE) && SK_SUPPORT_GPU
 bool Compiler::toPipelineStage(Program& program, PipelineStageArgs* outArgs) {