add flag to stage SkM44 change

See https://skia-review.googlesource.com/c/skia/+/272464

Test: make

Change-Id: I6048e1c37a72a8dc659af2d912585710f79af891
diff --git a/include/config/SkUserConfigManual.h b/include/config/SkUserConfigManual.h
index e9b4c64..bb2e261 100644
--- a/include/config/SkUserConfigManual.h
+++ b/include/config/SkUserConfigManual.h
@@ -24,6 +24,7 @@
   
   // Staging flags
   #define SK_LEGACY_PATH_ARCTO_ENDPOINT
+  #define SK_SUPPORT_EXPERIMENTAL_CANVAS44
  
   // Needed until we fix https://bug.skia.org/2440
   #define SK_SUPPORT_LEGACY_CLIPTOLAYERFLAG