Port faf64532

Original Commit Message:

    Indirections for external references are now handled completely in
    macro assemblers, which can produce more efficient code.

R=jgruber@chromium.org, joransiu@ca.ibm.com, michael_dawson@ca.ibm.com
BUG=
LOG=N

Change-Id: Ic94019affc7418e2d69944f5d8932502f7912684
Reviewed-on: https://chromium-review.googlesource.com/1099421Reviewed-by: Joran Siu <joransiu@ca.ibm.com>
Commit-Queue: Junliang Yan <jyan@ca.ibm.com>
Cr-Commit-Position: refs/heads/master@{#53714}