[svg] Add public.bzl defs for SVG source sets

Change-Id: I2c690b1e079494a3e1217330c3791d29bc37e27c
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/325337
Commit-Queue: Florin Malita <fmalita@google.com>
Reviewed-by: Tyler Denniston <tdenniston@google.com>
diff --git a/public.bzl b/public.bzl
index 0120325..f67fd40 100644
--- a/public.bzl
+++ b/public.bzl
@@ -981,3 +981,13 @@
     "Foundation",
     "UIKit",
 ]
+
+################################################################################
+## svg_lib
+################################################################################
+
+def svg_lib_hdrs():
+    return native.glob(["experimental/svg/model/*.h"])
+
+def svg_lib_srcs():
+    return native.glob(["experimental/svg/model/*.cpp"])