Add flag to stage Skia api change

See https://skia-review.googlesource.com/c/skia/+/349402

Bug: skia:7650
Change-Id: Ief9093e21c244eee791c7d7cc00125203d2e5009
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2606475Reviewed-by: Florin Malita <fmalita@chromium.org>
Commit-Queue: Mike Reed <reed@google.com>
Cr-Commit-Position: refs/heads/master@{#839980}

skia/config/SkUserConfig.h

@@ -229,6 +229,10 @@ SK_API void SkDebugf_FileLine(const char* file,
 #define GR_OP_ALLOCATE_USE_NEW
 #endif
 
+#ifndef SK_SUPPORT_LEGACY_ASYNCRESCALE_QUALITY
+#define SK_SUPPORT_LEGACY_ASYNCRESCALE_QUALITY
+#endif
+
 #ifndef SK_SUPPORT_LEGACY_IMPLICIT_FILTERQUALITY
 #define SK_SUPPORT_LEGACY_IMPLICIT_FILTERQUALITY
 #endif