Change function declarations and definitions related to sigvec.
Addressed upstream with the removal of sigvec in this commit:

commit 0781a7772ae1385fe8d7a734fdb35df81b1e6590
Author: Roland McGrath <roland@hack.frob.com>
Date:   Fri Nov 14 10:52:16 2014 -0800

    Remove sigvec.

diff --git a/include/signal.h b/include/signal.h
index a019395882176073..d9f279c9bf0aca3d 100644
--- a/include/signal.h
+++ b/include/signal.h
@@ -40,6 +40,7 @@ extern int __sigtimedwait (const sigset_t *__set, siginfo_t *__info,
 libc_hidden_proto (__sigtimedwait)
 extern int __sigqueue (__pid_t __pid, int __sig,
 		       const union sigval __val);
+struct sigvec;
 extern int __sigvec (int __sig, const struct sigvec *__vec,
 		     struct sigvec *__ovec);
 extern int __sigreturn (struct sigcontext *__scp);
diff --git a/signal/sigvec.c b/signal/sigvec.c
index e44daf1ab6fd2f39..21e304d944e46c18 100644
--- a/signal/sigvec.c
+++ b/signal/sigvec.c
@@ -24,10 +24,7 @@
    reset to SIG_DFL before `sv_handler' is entered.  If OVEC is non-NULL,
    it is filled in with the old information for SIG.  */
 int
-__sigvec (sig, vec, ovec)
-     int sig;
-     const struct sigvec *vec;
-     struct sigvec *ovec;
+__sigvec (int sig, const struct sigvec *vec, struct sigvec *ovec)
 {
   __set_errno (ENOSYS);
   return -1;
diff --git a/sysdeps/posix/sigvec.c b/sysdeps/posix/sigvec.c
index 89e3d44d88ce3ee5..6a3ccc8eaf8ae0a5 100644
--- a/sysdeps/posix/sigvec.c
+++ b/sysdeps/posix/sigvec.c
@@ -43,10 +43,7 @@ static struct sigvec_wrapper_data sigvec_wrapper_data[NSIG];
    reset to SIG_DFL before `sv_handler' is entered.  If OVEC is non-NULL,
    it is filled in with the old information for SIG.  */
 int
-__sigvec (sig, vec, ovec)
-     int sig;
-     const struct sigvec *vec;
-     struct sigvec *ovec;
+__sigvec (int sig, const struct sigvec *vec, struct sigvec *ovec)
 {
   struct sigaction old;
 
@@ -159,8 +156,7 @@ weak_alias (__sigvec, sigvec)
 
 #ifndef SA_RESETHAND
 static void
-sigvec_wrapper_handler (sig)
-     int sig;
+sigvec_wrapper_handler (int sig)
 {
   struct sigvec_wrapper_data *data;
   struct sigaction act;