scd: Fix for GNU/Linux suspend/resume.

* configure.ac (require_pipe_to_unblock_pselect): Default is "yes".
* scd/scdaemon.c (scd_kick_the_loop): Minor clean up.

--

Normally SIGCONT or SIGUSR2 works for unblocking pselect.  But on my
machine with GNU/Linux, when a machine is suspend/resume-ed, pselect
keeps blocked, while signal itself is delivered.

It's better to use pipe.

Signed-off-by: NIIBE Yutaka <gniibe@fsij.org>

configure.ac

@@ -639,7 +639,7 @@ have_android_system=no
 use_simple_gettext=no
 use_ldapwrapper=yes
 mmap_needed=yes
-require_pipe_to_unblock_pselect=no
+require_pipe_to_unblock_pselect=yes
 case "${host}" in
     *-mingw32*)
         # special stuff for Windoze NT
@@ -654,6 +654,7 @@ case "${host}" in
         have_w32_system=yes
         require_iconv=no
         use_ldapwrapper=no  # Fixme: Do this only for CE.
+        require_pipe_to_unblock_pselect=no
         case "${host}" in
           *-mingw32ce*)
             have_w32ce_system=yes

scd/scdaemon.c

@@ -1206,18 +1206,16 @@ start_connection_thread (void *arg)
 void
 scd_kick_the_loop (void)
 {
-  int ret;
-
   /* Kick the select loop.  */
 #ifdef HAVE_W32_SYSTEM
-  ret = SetEvent (the_event);
+  int ret = SetEvent (the_event);
   if (ret == 0)
     log_error ("SetEvent for scd_kick_the_loop failed: %s\n",
                w32_strerror (-1));
 #elif defined(HAVE_PSELECT_NO_EINTR)
   write (notify_fd, "", 1);
 #else
-  ret = kill (main_thread_pid, SIGCONT);
+  int ret = kill (main_thread_pid, SIGCONT);
   if (ret < 0)
     log_error ("SetEvent for scd_kick_the_loop failed: %s\n",
                gpg_strerror (gpg_error_from_syserror ()));