[GN] Add support for disabling opts via SK_BUILD_NO_OPTS define.

bench/SkBlend_optsBench.cpp

Index: bench/SkBlend_optsBench.cpp
diff --git a/bench/SkBlend_optsBench.cpp b/bench/SkBlend_optsBench.cpp
index 08c3d7fd4b870536ca2c0eae16f645d8ff0bc94e..29f3ed8331f4d835d46a6143f99e7481fe5f9fa5 100644
--- a/bench/SkBlend_optsBench.cpp
+++ b/bench/SkBlend_optsBench.cpp
@@ -151,7 +151,7 @@ private:
     typedef Benchmark INHERITED;
 };
 
-#if defined(SK_CPU_X86) && !defined(SK_BUILD_FOR_IOS)
+#if defined(SK_CPU_X86) && !defined(SK_BUILD_NO_OPTS)
 #define BENCHES(fileName)                                                        \
 DEF_BENCH( return new LinearSrcOverBench<SrcOverVSkOptsBruteForce>(fileName); )  \
 DEF_BENCH( return new LinearSrcOverBench<SrcOverVSkOptsTrivial>(fileName); )     \