add flag for future Skia CL

see https://skia-review.googlesource.com/c/5844/

BUG=
NOTRY=True

Review-Url: https://codereview.chromium.org/2573623002
Cr-Commit-Position: refs/heads/master@{#437920}

skia/config/SkUserConfig.h

@@ -228,6 +228,10 @@ SK_API void SkDebugf_FileLine(const char* file, int line, bool fatal,
 #   define SK_DISABLE_COLOR_XFORM_PIPELINE
 #endif
 
+#ifndef    SK_SUPPORT_EXOTIC_CLIPOPS
+#   define SK_SUPPORT_EXOTIC_CLIPOPS
+#endif
+
 #ifndef    SK_SUPPORT_LEGACY_IMAGE_ENCODER_CLASS
 #   define SK_SUPPORT_LEGACY_IMAGE_ENCODER_CLASS
 #endif