Introduce prototype-style definitions for various *at functions.

Upstream, these function definitions were removed in:

commit 754a15c61cd6834685386a134d0a0fed5f3ac4c1

Author: Joseph Myers <joseph@codesourcery.com>

Date:   Tue Sep 30 14:32:08 2014 +0000

    Move some *at definitions to syscalls.list (bug 14138).

diff --git a/sysdeps/unix/sysv/linux/fchownat.c b/sysdeps/unix/sysv/linux/fchownat.c

index 624804fa8cbfd8a1..0673118ad1c72958 100644

--- a/sysdeps/unix/sysv/linux/fchownat.c

+++ b/sysdeps/unix/sysv/linux/fchownat.c

@@ -29,12 +29,7 @@

 /* Change the owner and group of FILE.  */

 int

-fchownat (fd, file, owner, group, flag)

-     int fd;

-     const char *file;

-     uid_t owner;

-     gid_t group;

-     int flag;

+fchownat (int fd, const char *file, uid_t owner, gid_t group, int flag)

 {

   int result;

diff --git a/sysdeps/unix/sysv/linux/futimesat.c b/sysdeps/unix/sysv/linux/futimesat.c

index e3d034f800dfe61b..77f320d94aef5435 100644

--- a/sysdeps/unix/sysv/linux/futimesat.c

+++ b/sysdeps/unix/sysv/linux/futimesat.c

@@ -29,10 +29,7 @@

 /* Change the access time of FILE relative to FD to TVP[0] and

    the modification time of FILE to TVP[1].  */

 int

-futimesat (fd, file, tvp)

-     int fd;

-     const char *file;

-     const struct timeval tvp[2];

+futimesat (int fd, const char *file, const struct timeval tvp[2])

 {

   int result;

diff --git a/sysdeps/unix/sysv/linux/linkat.c b/sysdeps/unix/sysv/linux/linkat.c

index 90e0a79a7014ab72..0526861c007d773f 100644

--- a/sysdeps/unix/sysv/linux/linkat.c

+++ b/sysdeps/unix/sysv/linux/linkat.c

@@ -27,12 +27,7 @@

 /* Make a link to FROM named TO but relative paths in TO and FROM are

    interpreted relative to FROMFD and TOFD respectively.  */

 int

-linkat (fromfd, from, tofd, to, flags)

-     int fromfd;

-     const char *from;

-     int tofd;

-     const char *to;

-     int flags;

+linkat (int fromfd, const char *from, int tofd, const char *to, int flags)

 {

   int result;

diff --git a/sysdeps/unix/sysv/linux/mkdirat.c b/sysdeps/unix/sysv/linux/mkdirat.c

index c5ac40ad70c78b62..3989c13f6d511389 100644

--- a/sysdeps/unix/sysv/linux/mkdirat.c

+++ b/sysdeps/unix/sysv/linux/mkdirat.c

@@ -28,10 +28,7 @@

 /* Create a new directory with permission bits MODE.  But interpret

    relative PATH names relative to the directory associated with FD.  */

 int

-mkdirat (fd, file, mode)

-     int fd;

-     const char *file;

-     mode_t mode;

+mkdirat (int fd, const char *file, mode_t mode)

 {

   int res;

diff --git a/sysdeps/unix/sysv/linux/readlinkat.c b/sysdeps/unix/sysv/linux/readlinkat.c

index 1638cbb38063477e..05ac0c31743e0d09 100644

--- a/sysdeps/unix/sysv/linux/readlinkat.c

+++ b/sysdeps/unix/sysv/linux/readlinkat.c

@@ -29,11 +29,7 @@

 /* Read the contents of the symbolic link PATH relative to FD into no

    more than LEN bytes of BUF.  */

 ssize_t

-readlinkat (fd, path, buf, len)

-     int fd;

-     const char *path;

-     char *buf;

-     size_t len;

+readlinkat (int fd, const char *path, char *buf, size_t len)

 {

   int result;

diff --git a/sysdeps/unix/sysv/linux/renameat.c b/sysdeps/unix/sysv/linux/renameat.c

index 7623f5230306baaf..6b9e87016b17ab6c 100644

--- a/sysdeps/unix/sysv/linux/renameat.c

+++ b/sysdeps/unix/sysv/linux/renameat.c

@@ -104,11 +104,7 @@ __atfct_seterrno_2 (int errval, int fd1, const char *buf1, int fd2,

 /* Rename the file OLD relative to OLDFD to NEW relative to NEWFD.  */

 int

-renameat (oldfd, old, newfd, new)

-     int oldfd;

-     const char *old;

-     int newfd;

-     const char *new;

+renameat (int oldfd, const char *old, int newfd, const char *new)

 {

   int result;

diff --git a/sysdeps/unix/sysv/linux/symlinkat.c b/sysdeps/unix/sysv/linux/symlinkat.c

index 7e3812914c99ad8c..c8f8be9892dc41db 100644

--- a/sysdeps/unix/sysv/linux/symlinkat.c

+++ b/sysdeps/unix/sysv/linux/symlinkat.c

@@ -28,10 +28,7 @@

 /* Make a symbolic link to FROM named TO relative to TOFD.  */

 int

-symlinkat (from, tofd, to)

-     const char *from;

-     int tofd;

-     const char *to;

+symlinkat (const char *from, int tofd, const char *to)

 {

   int result;

diff --git a/sysdeps/unix/sysv/linux/unlinkat.c b/sysdeps/unix/sysv/linux/unlinkat.c

index 7c50a2a914486808..d4beb82b065068f7 100644

--- a/sysdeps/unix/sysv/linux/unlinkat.c

+++ b/sysdeps/unix/sysv/linux/unlinkat.c

@@ -29,10 +29,7 @@

 /* Remove the link named NAME.  */

 int

-unlinkat (fd, file, flag)

-     int fd;

-     const char *file;

-     int flag;

+unlinkat (int fd, const char *file, int flag)

 {

   int result;