headers_check fix: x86, prctl.h

fix the following 'make headers_check' warning:

  usr/include/asm/prctl.h:10: extern's make no sense in userspace
Signed-off-by: Jaswinder Singh Rajput <jaswinderrajput@gmail.com>

arch/x86/include/asm/prctl.h

@@ -6,8 +6,4 @@
 #define ARCH_GET_FS 0x1003
 #define ARCH_GET_GS 0x1004
 
-#ifdef CONFIG_X86_64
-extern long sys_arch_prctl(int, unsigned long);
-#endif /* CONFIG_X86_64 */
-
 #endif /* _ASM_X86_PRCTL_H */

arch/x86/include/asm/syscalls.h

@@ -74,6 +74,7 @@ asmlinkage long sys_vfork(struct pt_regs *);
 asmlinkage long sys_execve(char __user *, char __user * __user *,
 			   char __user * __user *,
 			   struct pt_regs *);
+long sys_arch_prctl(int, unsigned long);
 
 /* kernel/ioport.c */
 asmlinkage long sys_iopl(unsigned int, struct pt_regs *);