Merge changes Ic4817b31,If0be0700,I7c7d88c7,I260b0a1c,I4761bd33, ... into master-legacy

* changes:
  [UPSTREAM][IfConversion] Correctly handle cases where analyzeBranch fails.
  [BACKPORT][IR] CallBrInst: scan+update arg list when indirect dest list changes
  [UPSTREAM][IfConversion] Fix diamond conversion with unanalyzable branches.
  [UPSTREAM] Reland "[ARM] push LR before __gnu_mcount_nc"
  [UPSTREAM]Ignore indirect branches from callbr.
  [UPSTREAM][CodeGen] Require a name for a block addr target
  [UPSTREAM][MC] Don't recreate a label if it's already used