- Fix codegen for pc relative constant (e.g. JT) in thumb mode:

- Fix codegen for pc relative constant (e.g. JT) in thumb mode:
        .set PCRELV0, (LJTI1_0_0-(LPCRELL0+4))
LPCRELL0:
        add r1, pc, #PCRELV0
This is not legal since add r1, pc, #c requires the constant be a multiple of 4.
Do the following instead:
        .set PCRELV0, (LJTI1_0_0-(LPCRELL0+4))
LPCRELL0:
        mov r1, #PCRELV0
        add r1, pc

- In thumb mode, it's not possible to use .set generate a pc relative stub
  address. The stub is ARM code which is in a different section from the thumb
  code. Load the value from a constpool instead.
- Some asm printing clean up.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@33664 91177308-0d34-0410-b5e6-96231b3b80d8