libbb: introduce bb_signals and bb_signals_recursive,

which sets same handler for many signals. sig_catch is nuked
(bb_signals_recursive is more descriptive name).
*: use them as appropriate. 

function                                             old     new   delta
bb_signals_recursive                                   -      95     +95
bb_signals                                             -      52     +52
run_command                                          258     273     +15
svlogd_main                                         1368    1377      +9
runsv_main                                          1746    1752      +6
runsvdir_main                                       1643    1646      +3
UNSPEC_print                                          64      66      +2
time_main                                           1128    1127      -1
...
resize_main                                          246     210     -36
sig_catch                                             63       -     -63
set_fatal_sighandler                                  85      14     -71
------------------------------------------------------------------------------
(add/remove: 2/1 grow/shrink: 5/24 up/down: 182/-548)        Total: -366 bytes

1 files changed, 6 insertions, 4 deletions

diff --git a/networking/slattach.c b/networking/slattach.c
index 17df4fa9e..e501d82e1 100644
--- a/networking/slattach.c
+++ b/networking/slattach.c
@@ -175,10 +175,12 @@ int slattach_main(int argc, char **argv)
 
         /* Trap signals in order to restore tty states upon exit */
         if (!(opt & OPT_e_quit)) {
-                signal(SIGHUP, sig_handler);
-                signal(SIGINT, sig_handler);
-                signal(SIGQUIT, sig_handler);
-                signal(SIGTERM, sig_handler);
+                bb_signals(0
+                        + (1 << SIGHUP)
+                        + (1 << SIGINT)
+                        + (1 << SIGQUIT)
+                        + (1 << SIGTERM)
+                        , sig_handler);
         }
 
         /* Open tty */