add legacy flag

needed only so long as legacy picture-ptr-factory is being used

BUG=skia:
GOLD_TRYBOT_URL= https://gold.skia.org/search?issue=2237843002

TBR=
NOTRY=True

Review-Url: https://codereview.chromium.org/2237843002
diff --git a/gyp/skia_for_android_framework_defines.gypi b/gyp/skia_for_android_framework_defines.gypi
index fbeb3e7..26f6998 100644
--- a/gyp/skia_for_android_framework_defines.gypi
+++ b/gyp/skia_for_android_framework_defines.gypi
@@ -29,6 +29,7 @@
       'SK_SUPPORT_LEGACY_IMAGEFACTORY',
       'SK_SUPPORT_LEGACY_XFERMODE_PTR',
       'SK_IGNORE_GPU_DITHER',
+      'SK_SUPPORT_LEGACY_PICTUREINSTALLPIXELREF',
     ],
   },
 }