xtrans.m4: remove AC_TYPE_SIGNAL and Imake SIGNALRETURNSINT

Assume signal handlers return void, as C89 requires

Drops use of autoconf's obsolete AC_TYPE_SIGNAL and Imake's even more
obsolete SIGNALRETURNSINT.

None of the modules including xtrans.m4 uses RETSIGTYPE from autoconf.

Signed-off-by: Gaetan Nadon <memsize@videotron.ca>

Xtransutil.c

@@ -306,24 +306,12 @@ static jmp_buf env;
 #ifdef SIGALRM
 static volatile int nameserver_timedout = 0;
 
-static
-#ifdef RETSIGTYPE /* set by autoconf AC_TYPE_SIGNAL */
-RETSIGTYPE
-#else /* Imake */
-#ifdef SIGNALRETURNSINT
-int
-#else
-void
-#endif
-#endif
+static void
 nameserver_lost(int sig _X_UNUSED)
 {
   nameserver_timedout = 1;
   longjmp (env, -1);
   /* NOTREACHED */
-#ifdef SIGNALRETURNSINT
-  return -1;				/* for picky compilers */
-#endif
 }
 #endif /* SIGALARM */
 

xtrans.m4

@@ -100,7 +100,6 @@ AC_INCLUDES_DEFAULT
 # that use Xtrans functions
 AC_DEFUN([XTRANS_CONNECTION_FLAGS],[
  AC_REQUIRE([AC_CANONICAL_HOST])
- AC_REQUIRE([AC_TYPE_SIGNAL])
  [case $host_os in
 	mingw*)	unixdef="no"   ;;
 	*)	unixdef="yes"  ;;