Implement the ARM-specific struct layout ABI in exportable functions parameters for rs. Add the ABI-compliant #args when needed.
My old code inadvertently assumed x86 ABIs for structs, but ARM ABI/calling convention is tricky here, compared to x86's. Also, fixed the type promotion problem.
Note that the most portable fix is to add a shim layer in Clang which is a BIG undertaking like PNaCl. Let's put in the potential fix for b/2988615 now.

Change-Id: I1d9fe4d803485b55bb72112ea8e17c1f4a19dd32
8 files changed