Finally eliminate printMCInst and send instructions through

the streamer.  Demo:

$ cat t.ll 
define i32 @test() nounwind {
  ret i32 42
}
$ llc t.ll -o -
...
_test: 
	movl	$42, %eax
	ret
$ llc t.ll -o t.o -filetype=obj
$ otool -tv t.o 
t.o:
(__TEXT,__text) section
_test:
00000000	movl	$0x0000002a,%eax
00000005	ret

llvm-svn: 95179