Fix skip_unimplemented for filetype=obj in ARM.

Fixes generation of emit text fixup code in integrated ARM assembler to
properly reset the text fixup flag when skipping unimplemented
instructions.

Also fixes broken assertion for the "vmul" instruction.

BUG=None
R=stichnot@chromium.org

Review URL: https://codereview.chromium.org/1656023002 .
3 files changed