Revert "Rename openDexFileNative to openDexFile."

https://android-review.googlesource.com/#/c/103383/ introduces
absolute paths so we need back the old method name

Bug: 16644204
Bug: 16930747

This reverts commit 350b626e.

(cherry picked from commit a2069c71)

Change-Id: I55c8cb31bb79b1ed8ea51f63ec504d77f76a582a