Fix PR3994: LLVMMatchType arguments do not refer to absolute return value

Fix PR3994: LLVMMatchType arguments do not refer to absolute return value
and argument positions but only to the overloaded intrinsic parameters.
Keep a separate list of these overloaded parameters in CodeGenTarget.cpp
so they can be resolved easily.  Remove assertions from IntrinsicEmitter.cpp:
they were harmless but confusing, and the assertions elsewhere in TableGen
will catch any incorrect values.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@69316 91177308-0d34-0410-b5e6-96231b3b80d8