syscall: don't use pt_regs in clone_linux.c

    
    It's unnecessary and it reportedly breaks the build on arm64 GNU/Linux.
    
    Reviewed-on: https://go-review.googlesource.com/30978

From-SVN: r241084

gcc/go/gofrontend/MERGE

-f38ba8837a0c961e18d982930e192132870f3836
+6c9070324d5b7c8483bc7c17b0a8faaa1fb1ae30
 
 The first line of this file holds the git revision number of the last
 merge done from the gofrontend repository.

libgo/go/syscall/clone_linux.c

@@ -5,18 +5,17 @@
    license that can be found in the LICENSE file.  */
 
 #include <errno.h>
-#include <asm/ptrace.h>
 #include <sys/syscall.h>
 
 #include "runtime.h"
 
 long rawClone (unsigned long flags, void *child_stack, void *ptid,
-	       void *ctid, struct pt_regs *regs)
+	       void *ctid, void *regs)
   __asm__ (GOSYM_PREFIX "syscall.rawClone")
   __attribute__ ((no_split_stack));
 
 long
-rawClone (unsigned long flags, void *child_stack, void *ptid, void *ctid, struct pt_regs *regs)
+rawClone (unsigned long flags, void *child_stack, void *ptid, void *ctid, void *regs)
 {
 #if defined(__arc__) || defined(__aarch64__) || defined(__arm__) || defined(__mips__) || defined(__hppa__) || defined(__powerpc__) || defined(__score__) || defined(__i386__) || defined(__xtensa__)
   // CLONE_BACKWARDS