Fix the rest of rdar://8318441 which happens when a raw_fd_ostream

(e.g. errs()) fails in close() due to (e.g.) a broken pipe.  As
previously written, the had_error() flag would get set and then
the raw_ostream dtor would report a fatal error.  There is nothing
the client can do about this and we have no way to report the error,
so just eat it.

llvm-svn: 111321