clean up the asmprinter interface a bit, rename a few

clean up the asmprinter interface a bit, rename a few
"Print" methods to "Emit".  Emit is something that goes
to an mc streamer, Print is something that goes to a
raw_ostream (for inline asm)

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@100337 91177308-0d34-0410-b5e6-96231b3b80d8