Restore ETC1 compressed texture support.

Brings back GL ETC1 support and adds Vulkan support as well.

Bug: skia:8684
Change-Id: Ie65da0a3172793081f0e4072f161bfb9b14678bc
Reviewed-on: https://skia-review.googlesource.com/c/179724
Commit-Queue: Jim Van Verth <jvanverth@google.com>
Reviewed-by: Brian Salomon <bsalomon@google.com>
Reviewed-by: Robert Phillips <robertphillips@google.com>
diff --git a/public.bzl b/public.bzl
index 60ce79d..6a3ceba 100644
--- a/public.bzl
+++ b/public.bzl
@@ -276,7 +276,7 @@
             "src/codec/*Webp*.cpp",
             "src/codec/*Png*",
         ]
-    return native.glob(["src/codec/*.cpp", "third_party/gif/*.cpp"], exclude = exclude)
+    return native.glob(["src/codec/*.cpp", "third_party/etc1/*.cpp", "third_party/gif/*.cpp"], exclude = exclude)
 
 # Platform-dependent SRCS for google3-default platform.
 BASE_SRCS_UNIX = struct(
@@ -414,6 +414,7 @@
     "src/shaders/gradients",
     "src/sksl",
     "src/utils",
+    "third_party/etc1",
     "third_party/gif",
 ]