Using hidden files are rather antisocial, and rather pointless in this
particular context. Change .stdout and .stderr to simply stdout and
stderr.
Signed-off-by: H. Peter Anvin <hpa@zytor.com>
Permit opcode names to be used as labels if and only if they are
succeeded by a colon. Opcode names occurring when parsing expressions
are all treated as labels; a leading colon occurred when parsing an
instruction forces a parser restart with the instruction forcibly
treated as an identifier.
