Alpha: Add memory clobbers to `builtin_longjmp' expansion

Add the same memory clobbers to `builtin_longjmp' for Alpha as with
commit 41439bf6 ("builtins.c (expand_builtin_longjmp): Added two
memory clobbers."), to prevent instructions that access memory via the
frame or stack pointer from being moved across the write to the frame
pointer.

	gcc/
	* config/alpha/alpha.md (builtin_longjmp): Add memory clobbers.

gcc/config/alpha/alpha.md

@@ -5005,6 +5005,8 @@
   rtx pv = gen_rtx_REG (Pmode, 27);
 
   /* This bit is the same as expand_builtin_longjmp.  */
+  emit_clobber (gen_rtx_MEM (BLKmode, gen_rtx_SCRATCH (VOIDmode)));
+  emit_clobber (gen_rtx_MEM (BLKmode, hard_frame_pointer_rtx));
   emit_move_insn (hard_frame_pointer_rtx, fp);
   emit_move_insn (pv, lab);
   emit_stack_restore (SAVE_NONLOCAL, stack);