this completes the basic port of ARM constant islands to Mips16.
More testing, code review, cleanup is in order but basically everything
seems to be working. A bug in gas is preventing some of the runtime
testing but I hope to resolve this soon.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@196331 91177308-0d34-0410-b5e6-96231b3b80d8
