libbb: introduse and use signal_[no_]SA_RESTART_empty_mask and sigaction_set

signal_SA_RESTART_empty_mask                           -      65     +65
signal_no_SA_RESTART_empty_mask                        -      54     +54
dd_main                                             1325    1369     +44
sigaction_set                                          -      19     +19
dname_enc                                            373     377      +4
UNSPEC_print                                          64      66      +2
setsignal                                            296     294      -2
bb_signals_recursive                                  95      92      -3
bb_askpass                                           367     361      -6
inetd_main                                          1810    1797     -13
rx_main                                              912     883     -29
sigdelset                                             32       -     -32
__sigdelset                                           32       -     -32
__GI_sigdelset                                        32       -     -32
sighup_handler                                        84      37     -47
arping_main                                         1844    1797     -47
fsck_main                                           1869    1807     -62
run_list                                            1917    1844     -73
vlock_main                                           492     409     -83
progressmeter                                        883     798     -85
handle_incoming_and_exit                            2737    2651     -86
------------------------------------------------------------------------------
(add/remove: 3/3 grow/shrink: 3/12 up/down: 188/-632)        Total: -444 bytes

1 files changed, 2 insertions, 7 deletions

diff --git a/networking/wget.c b/networking/wget.c
index 36a83560a..a77a2add7 100644
--- a/networking/wget.c
+++ b/networking/wget.c
@@ -144,13 +144,8 @@ static void progressmeter(int flag)
                 transferred = 0;
                 fputc('\n', stderr);
         } else {
-                if (flag == -1) {
-                        /* first call to progressmeter */
-                        struct sigaction sa;
-                        sa.sa_handler = progressmeter;
-                        sigemptyset(&sa.sa_mask);
-                        sa.sa_flags = SA_RESTART;
-                        sigaction(SIGALRM, &sa, NULL);
+                if (flag == -1) { /* first call to progressmeter */
+                        signal_SA_RESTART_empty_mask(SIGALRM, progressmeter);
                 }
                 alarm(1);
         }