Pass charset to XmlPullParser.setInput instead of null

Passing null to XmlPullParser.setInput forces it to do additional
work, which can be easily avoided if we know the charset beforehand.

bug: b/20849543

(cherry picked from commit 9e9e2e73c6ec7bece20268196dc89ad0c8bafad4)

Change-Id: Iaff97be9df2d0f99d7af8f19f65934439c9658e2
26 files changed