Fix for sleep issue in bash loadable builtins

Replaced select() with pselect() and Blocked the 
SIGCHLD signal with sigprocmask() during the sleep process.

Signed-off-by: Thiruvadi Rajaraman <trajaraman@mvista.com>

  
Index: bash-4.2/lib/sh/ufuncs.c
===================================================================
--- bash-4.2.orig/lib/sh/ufuncs.c	2009-01-08 19:30:47.000000000 +0530
+++ bash-4.2/lib/sh/ufuncs.c	2017-12-04 15:53:09.576891443 +0530
@@ -19,7 +19,7 @@
 */
 
 #include "config.h"
-
+#include <signal.h>
 #include "bashtypes.h"
 
 #if defined (TIME_WITH_SYS_TIME)
@@ -86,11 +86,20 @@
      unsigned int sec, usec;
 {
   struct timeval tv;
+  sigset_t nmask, omask;
+  int ret;
+
+  sigemptyset(&nmask);
+  sigaddset(&nmask, SIGCHLD);
+  sigprocmask(SIG_BLOCK, &nmask, &omask);
 
   tv.tv_sec = sec;
   tv.tv_usec = usec;
 
-  return select(0, (fd_set *)0, (fd_set *)0, (fd_set *)0, &tv);
+  ret = pselect(0, (fd_set *)0, (fd_set *)0, (fd_set *)0, &tv, &nmask);
+  sigprocmask(SIG_SETMASK, &omask, NULL);
+
+  return ret;
 }
 #else /* !HAVE_TIMEVAL || !HAVE_SELECT */
 int