Add native-android fix to buildifier

[timpeut]

Also fixes a bug where the same global would be loaded multiple times.

[vladmos]

Thanks, could you please also modify the WARNINGS.md file? Warning messages point to it as a documentation page.

[timpeut]

Done

[vladmos]

Sorry, I've just realized: your fix will work for BUILD files, but in .bzl files the usage you need to match is not just android_library but native.android_library (and the other functions as well). In that case you'll need to both add a load and replace the node with a simple function call.

An example fix that matches native.<something>: https://github.com/bazelbuild/buildtools/blob/master/warn/warn_bazel.go#L47 . You'll basically need to do the same but in .bzl files, and you should only match CallExpr nodes with the X attribute equal to native.<your function> (which is a DotExpr node with X == Ident (Name == "native") and Name == "your_function_name".

[timpeut]

Added support for native.X