AAPT2 generates extra versions of XML binaries based on the sdkVersion
that attributes were introduced, up to v21. This should only happen for
sdkVersions that are > minSdkVersion, as everything else can be included
in the main configuration (e.g. "layout" instead of "layout-v4").
This change handles the merging of XML binary sdkVersions that were created
implicitly.
Bug: 30705740
Change-Id: I854843dd6dbaca52896cea0c24c70c900cec3e8e