[monitoring-plugins] Remove check for RETSIGTYPE in autoconf stuff

[RincewindsHat]

 Module: monitoring-plugins
 Branch: master
 Commit: 513929d796af668e977ca7981800c259304a2f25
 Author: RincewindsHat <12514511+RincewindsHat at users.noreply.github.com>
   Date: Sat Sep 23 12:31:33 2023 +0200
    URL: https://www.monitoring-plugins.org/repositories/monitoring-plugins/commit/?id=513929d

Remove check for RETSIGTYPE in autoconf stuff

autoupdate tells me, that since C89 I can safely assume RETSIGTYPE
is void.

Therefore to simplify things I removed the corresponding configure.ac
line and replaced all mentions of RETSIGTYPE with void.

---

 configure.ac       | 1 -
 lib/utils_cmd.h    | 2 +-
 plugins/netutils.h | 2 +-
 plugins/popen.c    | 8 ++++----
 plugins/popen.h    | 2 +-
 5 files changed, 7 insertions(+), 8 deletions(-)

diff --git a/configure.ac b/configure.ac
index a294b00..e6a40d3 100644
--- a/configure.ac
+++ b/configure.ac
@@ -621,7 +621,6 @@ AC_C_CONST
 AC_STRUCT_TM
 AC_TYPE_PID_T
 AC_TYPE_SIZE_T
-AC_TYPE_SIGNAL
 
 AC_CACHE_CHECK([for va_copy],ac_cv_HAVE_VA_COPY,[
 AC_TRY_LINK([#include <stdarg.h>
diff --git a/lib/utils_cmd.h b/lib/utils_cmd.h
index 1fc2968..f1b06c8 100644
--- a/lib/utils_cmd.h
+++ b/lib/utils_cmd.h
@@ -33,7 +33,7 @@ void cmd_init (void);
 #define CMD_NO_ASSOC 0x02    /* output.line won't point to buf */
 
 
-RETSIGTYPE timeout_alarm_handler (int);
+void timeout_alarm_handler (int);
 
 
 #endif /* _UTILS_CMD_ */
diff --git a/plugins/netutils.h b/plugins/netutils.h
index d7ee0dd..ea653e7 100644
--- a/plugins/netutils.h
+++ b/plugins/netutils.h
@@ -92,7 +92,7 @@ extern int econn_refuse_state;
 extern int was_refused;
 extern int address_family;
 
-RETSIGTYPE socket_timeout_alarm_handler (int) __attribute__((noreturn));
+void socket_timeout_alarm_handler (int) __attribute__((noreturn));
 
 /* SSL-Related functionality */
 #ifdef HAVE_SSL
diff --git a/plugins/popen.c b/plugins/popen.c
index b395f14..036bc60 100644
--- a/plugins/popen.c
+++ b/plugins/popen.c
@@ -50,9 +50,9 @@ extern FILE *child_process;
 FILE *spopen (const char *);
 int spclose (FILE *);
 #ifdef REDHAT_SPOPEN_ERROR
-RETSIGTYPE popen_sigchld_handler (int);
+void popen_sigchld_handler (int);
 #endif
-RETSIGTYPE popen_timeout_alarm_handler (int);
+void popen_timeout_alarm_handler (int);
 
 #include <stdarg.h>							/* ANSI C header file */
 #include <fcntl.h>
@@ -266,7 +266,7 @@ spclose (FILE * fp)
 }
 
 #ifdef REDHAT_SPOPEN_ERROR
-RETSIGTYPE
+void
 popen_sigchld_handler (int signo)
 {
 	if (signo == SIGCHLD)
@@ -274,7 +274,7 @@ popen_sigchld_handler (int signo)
 }
 #endif
 
-RETSIGTYPE
+void
 popen_timeout_alarm_handler (int signo)
 {
 	int fh;
diff --git a/plugins/popen.h b/plugins/popen.h
index a5dd8fa..1ea6963 100644
--- a/plugins/popen.h
+++ b/plugins/popen.h
@@ -5,7 +5,7 @@
 
 FILE *spopen (const char *);
 int spclose (FILE *);
-RETSIGTYPE popen_timeout_alarm_handler (int);
+void popen_timeout_alarm_handler (int);
 
 pid_t *childpid=NULL;
 int *child_stderr_array=NULL;