x86: restore standard stack frame layout and fix stack alignment.

Native x86 can contain SSE instructions, this requires 16-byte aligned stack
which is what GCC expects these days. Enforce this in dvmPlatformInvoke and
in mterp.

Also fix stack frame layout, so debuggers can produce backtraces across
dvmMterpStdRun invocations.

Change-Id: I43d00a6bf8210b7d3aa9276edabc08978084e4f2
5 files changed