re PR go/46959 (M68K Not Supported by Go)

	PR go/46959
	PR go/46960
	PR go/46961
	PR go/46962
	PR go/46963
	PR go/46964
Use __builtin_unwind_init rather than the SAVE_REGS hack.

From-SVN: r168500

libgo/runtime/go-go.c

@@ -25,21 +25,6 @@ extern void *__splitstack_find (void *, void *, size_t *, void **, void **,
 				void **);
 #endif
 
-/* We need to ensure that all callee-saved registers are stored on the
-   stack, in case they hold pointers.  */
-
-#if defined(__i386__)
- #ifndef __PIC__
-  #define SAVE_REGS asm ("" : : : "esi", "edi", "ebx")
- #else
-  #define SAVE_REGS asm ("" : : : "esi", "edi")
- #endif
-#elif defined(__x86_64__)
- #define SAVE_REGS asm ("" : : : "r12", "r13", "r14", "r15", "rbp", "rbx")
-#else
- #error must define SAVE_REGS
-#endif
-
 /* We stop the threads by sending them the signal GO_SIG_STOP and we
    start them by sending them the signal GO_SIG_START.  */
 
@@ -344,7 +329,7 @@ __go_run_goroutine_gc (int r)
      needed if we are called directly, since otherwise we might miss
      something that a function somewhere up the call stack is holding
      in a register.  */
-  SAVE_REGS;
+  __builtin_unwind_init ();
 
   stop_for_gc ();
 
@@ -433,7 +418,7 @@ __go_scanstacks (void (*scan) (byte *, int64))
   struct __go_thread_id *p;
 
   /* Make sure all the registers for this thread are on the stack.  */
-  SAVE_REGS;
+  __builtin_unwind_init ();
 
   me = pthread_self ();
   for (p = __go_all_thread_ids; p != NULL; p = p->next)