[ARM] Prefer indirect calls in minsize mode

[ARM] Prefer indirect calls in minsize mode

... When we emit several calls to the same function in the same basic block.

An indirect call uses a "BLX r0" instruction which has a 16-bit encoding. If many calls are made to the same target, this can enable significant code size reductions.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@275537 91177308-0d34-0410-b5e6-96231b3b80d8