libbb: unified config parser (By Vladimir Dronnikov)
mdev: use it

function                                             old     new   delta
config_read                                            -     400    +400
config_open                                            -      43     +43
config_close                                           -       9      +9
qrealloc                                              33      36      +3
compare_keys                                         735     737      +2
xstrtoull_range_sfx                                  296     295      -1
qgravechar                                           109     106      -3
get_address                                          181     178      -3
next_token                                           928     923      -5
sv_main                                             1228    1222      -6
find_main                                            418     406     -12
next_field                                            32       -     -32
make_device                                         1269    1184     -85
------------------------------------------------------------------------------
(add/remove: 3/1 grow/shrink: 2/7 up/down: 457/-147)          Total: 310 bytes

diff --git a/libbb/Kbuild b/libbb/Kbuild
index ab85ffc..7262006 100644
--- a/libbb/Kbuild
+++ b/libbb/Kbuild
@@ -63,6 +63,7 @@
 lib-y += mtab_file.o
 lib-y += obscure.o
 lib-y += parse_mode.o
+lib-y += parse_config.o
 lib-y += perror_msg.o
 lib-y += perror_msg_and_die.o
 lib-y += perror_nomsg.o