Fix the root cause of the bootstrap failure:
Fix the root cause of the bootstrap failure:

There was no way to check if a given register/mode pair was valid. We now return
an error code (-2) instead of asserting. If anyone thinks that an assert
at this point  is really needed, we can autogen a hasValidDwarfRegNum instead.

git-svn-id: a4a6f32337ebd29ad4763b423022f00f68d1c7b7@132236 91177308-0d34-0410-b5e6-96231b3b80d8

lodyagin/bare_cxx,lodyagin/bare_cxx,lodyagin/bare_cxx,lodyagin/bare_cxx,lodyagin/bare_cxx