Stop using sig_t

acinclude.m4 was adding to afsconfig.h some code to define sig_t as the
type of a signal handler.  This definition was in terms of RETSIGTYPE,
which is deprecated by Autoconf.  It also adds an unnecessary abstraction
for only two places in the AFS source code where it was used.  Remove it
and change those two spots to use the standard C declaration of the
function pointer.

Reviewed-on: http://gerrit.openafs.org/335
Tested-by: Simon Wilkinson <sxw@inf.ed.ac.uk>
Reviewed-by: Simon Wilkinson <sxw@inf.ed.ac.uk>
Reviewed-by: Derrick Brashear <shadow@dementia.org>

acinclude.m4

@@ -1603,13 +1603,6 @@ AC_CHECK_TYPE(ssize_t, int)
 AC_CHECK_TYPES(sig_t, , ,
   [#include <sys/types.h>
    #include <signal.h> ])
-AH_BOTTOM(
-[#ifndef HAVE_SIG_T
-#ifndef SIG_T_DEFINED
-#define SIG_T_DEFINED
-typedef RETSIGTYPE (*sig_t) ();
-#endif
-#endif])
 AC_CHECK_TYPE([sig_atomic_t], ,
     [AC_DEFINE([sig_atomic_t], [int],
         [Define to int if <signal.h> does not define.])],

src/kauth/user.c

@@ -160,7 +160,7 @@ ka_UserAuthenticateGeneral(afs_int32 flags, char *name, char *instance,
     struct ktc_encryptionKey key;
     afs_int32 code, dosetpag = 0;
 #if !defined(AFS_NT40_ENV) && !defined(AFS_LINUX20_ENV) && !defined(AFS_USR_LINUX20_ENV) && !defined(AFS_XBSD_ENV) || defined(AFS_FBSD_ENV)
-    sig_t old;
+    void (*old)(int);
 #endif
 
     if (reasonP)

src/sys/pioctl.c

@@ -56,7 +56,7 @@ lpioctl(char *path, int cmd, void *cmarg, int follow)
 #ifndef AFS_LINUX20_ENV
     /* As kauth/user.c says, handle smoothly the case where no AFS system call
      * exists (yet). */
-    sig_t old = signal(SIGSYS, SIG_IGN);
+    void (*old)(int) = signal(SIGSYS, SIG_IGN);
 #endif
 
 #if defined(AFS_LINUX20_ENV)