toolchain: Update revisions for Android

Also add spirv-headers, a new dependency for shaderc.
diff --git a/build-android/spirv-tools_revision_android b/build-android/spirv-tools_revision_android
index 9a829b9..2ce5d17 100644
--- a/build-android/spirv-tools_revision_android
+++ b/build-android/spirv-tools_revision_android
@@ -1 +1 @@
-469f0e8fd53b527ad410c46bf18eee327c9256a3
+e7a9e007384db16bc39dae01fadf4b73e754ab7e