make sksg a component

Change-Id: I81fcbecb6ae002bd1b61918514f5c836660c27cb
Reviewed-on: https://skia-review.googlesource.com/145883
Reviewed-by: Florin Malita <fmalita@chromium.org>
Commit-Queue: Mike Klein <mtklein@google.com>
diff --git a/modules/sksg/BUILD.gn b/modules/sksg/BUILD.gn
index d1527f4..89c005f 100644
--- a/modules/sksg/BUILD.gn
+++ b/modules/sksg/BUILD.gn
@@ -7,7 +7,7 @@
   include_dirs = [ "include" ]
 }
 
-source_set("sksg") {
+component("sksg") {
   import("sksg.gni")
   public_configs = [ ":public_config" ]
   sources = skia_sksg_sources