Fix AppRTCDemo crash under iOS due to the unaligned access in vld1
instruction in iSACFix codec, which is not allowed in iOS build.
BUG=4717
R=andrew@webrtc.org, jridges@masque.com
TEST=Run the AppRTCDemo
Change-Id: Ie5fbc9b8ae88cd00b243a8e65cab95b00362a9da
Review URL: https://codereview.webrtc.org/1182493006.
Cr-Commit-Position: refs/heads/master@{#9432}