Add SkCGUtils.h to public.bzl

Change-Id: Ia337c9f1d82f823159e4a9985992650b04b4b020
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/577956
Reviewed-by: Brian Osman <brianosman@google.com>
diff --git a/public.bzl b/public.bzl
index 18670f0..ddd48a7 100644
--- a/public.bzl
+++ b/public.bzl
@@ -232,6 +232,7 @@
     "include/utils/SkShadowUtils.h",
     "include/utils/SkTextUtils.h",
     "include/utils/SkTraceEventPhase.h",
+    "include/utils/mac/SkCGUtils.h",
 ]
 
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