Break the "IncludeFile" mechanism into its own header file and adjust other
files accordingly. Use this facility for the IntrinsicInst problem which
was the subject of PR800.
More to follow on this.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@28709 91177308-0d34-0410-b5e6-96231b3b80d8
