ARM: make assembly files compile Thumb2 with nop IT block.

ARM's UAL syntax allows the same assembly file to be compiled in both ARM and
Thumb mode. Conditional execution is handled by requiring the Thumb IT blocks,
but essentially ignoring them when compiling for ARM.

git-svn-id: https://llvm.org/svn/llvm-project/compiler-rt/trunk@194429 91177308-0d34-0410-b5e6-96231b3b80d8