fix openjdk-src build regression due to RUNTIME_ARRAY changes
add note about OpenJDK build infrastructure available on GitHub
reset alignment at inheritence boundary when iterating over fields

In type-generator, we were incorrectly calculating field offsets where
a class inherits from another class whose last field has a natural
alignment which is different from the native word size.  Surprisingly,
this only popped up when I built using the Android class library on a
64-bit system.
enable use of Android class library on 64-bit systems

This involved patching libcore.git to make it 64-bit safe.
Merge remote-tracking branch 'github/master' into dicej