libbb: introduce and use safe_waitpid (loops in EINTR)

*: use more approproate (shorter) versions of wait()

function                                             old     new   delta
safe_waitpid                                           -      48     +48
wait_any_nohang                                        -      17     +17
send_tree                                            365     369      +4
processorstop                                        432     435      +3
text_yank                                            110     108      -2
make_human_readable_str                              202     200      -2
crond_main                                          1368    1366      -2
handle_sigchld                                        49      43      -6
reapchild                                            166     159      -7
custom                                               260     250     -10
checkscript                                          191     177     -14
wait_nohang                                           17       -     -17
wait_pid                                              43       -     -43
------------------------------------------------------------------------------
(add/remove: 2/2 grow/shrink: 2/7 up/down: 72/-103)           Total: -31 bytes

1 files changed, 1 insertions, 2 deletions

diff --git a/runit/sv.c b/runit/sv.c
index e31adffed..a89e24439 100644
--- a/runit/sv.c
+++ b/runit/sv.c
@@ -333,8 +333,7 @@ static int checkscript(void)
                 bb_perror_msg(WARN"cannot %s child %s/check", "run", *service);
                 return 0;
         }
-        while (wait_pid(&w, pid) == -1) {
-                if (errno == EINTR) continue;
+        while (safe_waitpid(pid, &w, 0) == -1) {
                 bb_perror_msg(WARN"cannot %s child %s/check", "wait for", *service);
                 return 0;
         }