Make clang-tblgen backends functions instead of TableGenBackends.

Get rid of a bunch of header files. TableGen output should be unaffected.

Patch by Sean Silva!

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@158388 91177308-0d34-0410-b5e6-96231b3b80d8
14 files changed