AMR WB encoder: prevent OOB write in ACELP_4t64_fx

In ACELP_4t64_fx, when iterating over ind array, check index against
  array size to prevent OOB write, log an error if such an access
  was about to happen.

Bug: 132647222
Test: atest EncoderTest#testAMRWBEncoders
Change-Id: I33f476d94baec2feffc7bcccd0ad0481b8452518
(cherry picked from commit 82cb46d0)
Merged-in: I33f476d94baec2feffc7bcccd0ad0481b8452518
(cherry picked from commit 9a44849c)