The MCJIT doesn't seem to call getPointerForNamedFunction from the...

The MCJIT doesn't seem to call getPointerForNamedFunction from the MemoryManager anymore, switching to getSymbolAddress, which
it does call, and implementing it so that we once again look up external symbols in the JIT.

Also juked the error reporting from the JIT a little bit.

This resolves:
http://llvm.org/bugs/show_bug.cgi?id=22314

llvm-svn: 227217