[Fuchsia] Add OWNERS for Fuchsia-specific files under //skia.

Change-Id: Icea282ff9484b43f2cbc9cac1ea00f877f4fb669
Reviewed-on: https://chromium-review.googlesource.com/1142133
Reviewed-by: Leon Scroggins <scroggo@chromium.org>
Commit-Queue: Wez <wez@chromium.org>
Cr-Commit-Position: refs/heads/master@{#576649}

skia/OWNERS

@@ -14,4 +14,7 @@ scroggo@chromium.org
 senorblanco@chromium.org
 thakis@chromium.org
 
+# For Fuchsia-specific changes:
+per-file *_fuchsia*=file://build/fuchsia/OWNERS
+
 # COMPONENT: Internals>Skia