preproc: move %use package parsing to a separate routine
preproc: move %use package parsing to a separate routine

Move the parsing of %use package names to a separate routine, and stop
using get_id() for that purpose -- get_id() is wrong in a number of
ways.

This also means we can drop the error string argument to get_id().

Signed-off-by: H. Peter Anvin <8a453bad9912ffe59bc0f0b8abe03df9be19379e@zytor.com>

techkey/nasm,techkey/nasm,techkey/nasm,techkey/nasm,techkey/nasm