Pull up the following, requested by christos in ticket #776:

usr.bin/config/TODO                            up to 1.32
usr.bin/config/defs.h                          up to 1.105
usr.bin/config/files.c                          up to 1.37
usr.bin/config/gram.y                          up to 1.55
usr.bin/config/main.c                          up to 1.99
usr.bin/config/scan.l                          up to 1.30
usr.bin/config/sem.c                            up to 1.84
usr.bin/config/util.c                          up to 1.21

config(1): fix issue with incorrect handling of elifdef statements.

(martin)