The return value for signal() is standardized as void, as of C89;

AC_TYPE_SIGNAL is deprecated.

x11/config.h.in

@@ -75,9 +75,6 @@
 /* Define as the system defined limit for number of signals */
 #undef PDC_MAX_SIGNALS
 
-/* Define as the return type of signal handlers (`int' or `void'). */
-#undef RETSIGTYPE
-
 /* Define to 1 if you can safely include both <sys/time.h> and <time.h>. */
 #undef TIME_WITH_SYS_TIME
 

x11/configure.ac

@@ -59,7 +59,6 @@ AC_SUBST(MH_EXTRA_LIBS)
 MH_CHECK_CC_O
 
 dnl Checks for library functions.
-AC_TYPE_SIGNAL
 AC_CHECK_FUNCS(vsscanf usleep poll vsnprintf)
 
 dnl Check for X includes and X libraries

x11/pdcx11.h

@@ -136,7 +136,7 @@ int XC_read_socket(int, void *, int);
 int XC_write_display_socket_int(int);
 
 int XCursesSetupX(int argc, char *argv[]);
-RETSIGTYPE XCursesSigwinchHandler(int signo);
+void XCursesSigwinchHandler(int signo);
 
 #ifdef _HPUX_SOURCE
 # define FD_SET_CAST int *
@@ -161,7 +161,7 @@ extern int xc_display_sockets[2];
 extern int xc_key_sockets[2];
 extern int xc_exit_sock;
 
-typedef RETSIGTYPE (*signal_handler)();
+typedef void (*signal_handler)();
 
 signal_handler XCursesSetSignal(int, signal_handler);
 

x11/x11.c

@@ -531,7 +531,7 @@ signal_handler XCursesSetSignal(int signo, signal_handler action)
 #endif
 }
 
-RETSIGTYPE XCursesSigwinchHandler(int signo)
+void XCursesSigwinchHandler(int signo)
 {
     PDC_LOG(("%s:XCursesSigwinchHandler() - called: SIGNO: %d\n",
              XCLOGMSG, signo));
@@ -2797,7 +2797,7 @@ static void _handle_structure_notify(Widget w, XtPointer client_data,
     }
 }
 
-static RETSIGTYPE _handle_signals(int signo)
+static void _handle_signals(int signo)
 {
     int flag = CURSES_EXIT;