Generalize zlib utils dir for Skia build.

BUILD.gn

@@ -791,7 +791,8 @@ group("angle_compression") {
     ":angle_compression_config",
     "//third_party/zlib:zlib_config",
   ]
-  public_deps = [ "//third_party/zlib/google:compression_utils_portable" ]
+  public_deps =
+      [ "$angle_zlib_compression_utils_dir:compression_utils_portable" ]
 }
 
 angle_source_set("libANGLE_with_capture") {

gni/angle.gni

@@ -140,6 +140,10 @@ declare_args() {
   angle_enable_overlay = false
 }
 
+if (!defined(angle_zlib_compression_utils_dir)) {
+  angle_zlib_compression_utils_dir = "//third_party/zlib/google"
+}
+
 angle_common_configs = [
   angle_root + ":angle_release_asserts_config",
   angle_root + ":better_linux_stack_traces",