Introduce prototype-style function definitions for architecture-specific
gettimeofday implementations.

Upstream did this as part of:

commit 97554e4382e5d85eccf146b58f85aaad7e3d687c
Author: Adhemerval Zanella <adhemerval.zanella@linaro.com>
Date:   Fri Apr 17 11:48:51 2015 -0300

    Consolidate gettimeofday across aarch64/s390/tile

diff --git a/sysdeps/unix/sysv/linux/aarch64/gettimeofday.c b/sysdeps/unix/sysv/linux/aarch64/gettimeofday.c
index 90d115577bad42ec..0a43a1bf94432006 100644
--- a/sysdeps/unix/sysv/linux/aarch64/gettimeofday.c
+++ b/sysdeps/unix/sysv/linux/aarch64/gettimeofday.c
@@ -27,9 +27,7 @@
    putting it into *tv and *tz.  If tz is null, *tz is not filled.
    Returns 0 on success, -1 on errors.  */
 int
-__gettimeofday (tv, tz)
-     struct timeval *tv;
-     struct timezone *tz;
+__gettimeofday (struct timeval *tv, struct timezone *tz)
 {
   return INLINE_VSYSCALL (gettimeofday, 2, tv, tz);
 }
diff --git a/sysdeps/unix/sysv/linux/s390/gettimeofday.c b/sysdeps/unix/sysv/linux/s390/gettimeofday.c
index d897e1a6b68c069a..10777d17828fa9d0 100644
--- a/sysdeps/unix/sysv/linux/s390/gettimeofday.c
+++ b/sysdeps/unix/sysv/linux/s390/gettimeofday.c
@@ -28,9 +28,7 @@
    Returns 0 on success, -1 on errors.  */
 
 int
-__gettimeofday (tv, tz)
-     struct timeval *tv;
-     struct timezone *tz;
+__gettimeofday (struct timeval *tv, struct timezone *tz)
 {
   return INLINE_VSYSCALL (gettimeofday, 2, tv, tz);
 }