Fix multiple output file generation for AAPT2

Make R.stamp actually part of the same rule that creates R.java.
Otherwise if the generated sources directory is removed, we don't
regenerate R.java / Manifest.java.

Also move the package-export.apk and proguard options file into the same
rule.

Test: m telephony-common; rm out/target/common/obj/*/*_intermediates/src; m telephony-common
Change-Id: I71f6fcaf20593ca23271d52d15537aaa9ef4cc77