ARM: Fix ELF global base reg intialization.

The create machine code wasn't properly in SSA, which the machine verifier
properly complains about. Now that fast-isel is closer to verifier clean,
errors like this show up more clearly.

Additionally, the Thumb pseudo tPICADD was used for both ARM and Thumb
mode functions, which is obviously wrong. Fix that along the way.

Test case is part of the following commit which will finish making an
additional fast-isel test verifier clean an enable it for the
regression test suite. This commit is separate since its not just
a verifier cleanup, but an actual correctness issue.

rdar://12594152 (for the fast-isel verifier aspects)

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@189269 91177308-0d34-0410-b5e6-96231b3b80d8
ARM: FastISel verifier error cleanup.

Constant pool and global value reference instructions need more
restricted register classes than plain GPR.

rdar://12594152

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@189270 91177308-0d34-0410-b5e6-96231b3b80d8
Dummy code to silence warning from 4189266

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@189272 91177308-0d34-0410-b5e6-96231b3b80d8
ARM: Constrain regclass for TSTri instruction.

Get the register class right for the TST instruction. This keeps the
machine verifier happy, enabling us to turn it on for another test.

rdar://12594152

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@189274 91177308-0d34-0410-b5e6-96231b3b80d8
ARM: Enable machine verifier for a few more tests.

Now that fast-isel is in better shape, we can enable the machine
verifier for these tests, too.

rdar://12594152

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@189275 91177308-0d34-0410-b5e6-96231b3b80d8