Revert "Revert "Merge remote-tracking branch 'goog/master-skia' into goog/master""

When I broke android yesterday we reverted this merge to fix the breakage.
Undoing that revert so we can pull in the fix from Skia.
diff --git a/gyp/ktx.gyp b/gyp/ktx.gyp
index 1ee0349..e01ef1f 100644
--- a/gyp/ktx.gyp
+++ b/gyp/ktx.gyp
@@ -13,6 +13,7 @@
     'include_dirs' : [
       '../third_party/ktx',
       '../include/gpu',
+      '../include/private',
       '../src/core',
       '../src/gpu',
       '../src/utils',