Android package names are more strict (ASCII only) than Java package names.
Also fixed an issue where trailing underscores were disallowed in Android
package names.
Bug: 68468089
Test: make aapt2_tests
Merged-In: I1052e9e82b6617db6065ce448d9bf7972bb68d59
Change-Id: I1052e9e82b6617db6065ce448d9bf7972bb68d59