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, 12 insertions, 8 deletions

diff --git a/include/libbb.h b/include/libbb.h
index f505cc718..67afcdf94 100644
--- a/include/libbb.h
+++ b/include/libbb.h
@@ -274,14 +274,18 @@ char *xrealloc_getcwd_or_warn(char *cwd);
 
 char *xmalloc_follow_symlinks(const char *path);
 
-//TODO: signal(sid, f) is the same? then why?
-extern void sig_catch(int,void (*)(int));
-//#define sig_ignore(s) (sig_catch((s), SIG_IGN))
-//#define sig_uncatch(s) (sig_catch((s), SIG_DFL))
-extern void sig_block(int);
-extern void sig_unblock(int);
-/* UNUSED: extern void sig_blocknone(void); */
-extern void sig_pause(void);
+//enum {
+//      BB_SIGS_FATAL = ,
+//};
+void bb_signals(int sigs, void (*f)(int));
+/* Unlike signal() and bb_signals, sets handler with sigaction()
+ * and in a way that while signal handler is run, no other signals
+ * will be blocked: */
+void bb_signals_recursive(int sigs, void (*f)(int));
+void sig_block(int);
+void sig_unblock(int);
+/* UNUSED: void sig_blocknone(void); */
+void sig_pause(void);
 
 
 void xsetgid(gid_t gid);