Introduce prototype-style definition for execve.  Upstream, the
old-style function definition was removed in:

commit 6268f532b6c6be7971cb57883d042bd771966548
Author: Joseph Myers <joseph@codesourcery.com>
Date:   Wed Oct 1 20:58:20 2014 +0000

    Move execve to syscalls.list (bug 14138).

diff --git a/sysdeps/unix/sysv/linux/execve.c b/sysdeps/unix/sysv/linux/execve.c
index 34fd14bf6afc5417..872b150784d41007 100644
--- a/sysdeps/unix/sysv/linux/execve.c
+++ b/sysdeps/unix/sysv/linux/execve.c
@@ -25,10 +25,7 @@
 /* Consider moving to syscalls.list.  */
 
 int
-__execve (file, argv, envp)
-     const char *file;
-     char *const argv[];
-     char *const envp[];
+__execve (const char *file, char *const argv[], char *const envp[])
 {
   return INLINE_SYSCALL (execve, 3, file, argv, envp);
 }