Make the fakebins executable to please new symlink target check.

https://r.android.com/1439191 added a check that the prebuilt is
executable for binaries. That failed on the ART APEX check fakebins,
although it didn't abort the builds.

Test: m art-check-{release,debug,testing}-apex-gen-fakebin
Change-Id: I7ed2421e5c800f7dfe09d7ec9c9cfe5123f046e6
1 file changed