add SkGraphics::AllowJIT()

Change-Id: I82aeea670c19e08e51ddc094f66f41244e4f5ec8
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/308497
Reviewed-by: Mike Reed <reed@google.com>
Commit-Queue: Mike Klein <mtklein@google.com>

include/core/SkGraphics.h

@@ -167,6 +167,11 @@ public:
      */
     static ImageGeneratorFromEncodedDataFactory
                     SetImageGeneratorFromEncodedDataFactory(ImageGeneratorFromEncodedDataFactory);
+
+    /**
+     *  Call early in main() to allow Skia to use a JIT to accelerate CPU-bound operations.
+     */
+    static void AllowJIT();
 };
 
 class SkAutoGraphics {

src/core/SkGraphics.cpp

@@ -132,3 +132,9 @@ void SkGraphics::PurgeFontCache() {
     SkStrikeCache::GlobalStrikeCache()->purgeAll();
     SkTypefaceCache::PurgeAll();
 }
+
+extern bool gSkVMAllowJIT;
+
+void SkGraphics::AllowJIT() {
+    gSkVMAllowJIT = true;
+}