Make strlist_free() take a pointer to a pointer, so we can set it to
NULL.
Buffer warnings on a strlist until we either get an error or we are in
pass 2. Hopefully this should let us get rid of a lot of the ERR_PASS*
bullshit, which far too often causes messages to get lost.
asm/labels.c contains one example of a warning that cannot be made
correct with a specific pass number.
Signed-off-by: H. Peter Anvin (Intel) <hpa@zytor.com>
374312cde4