Fix Sparc GDB regression

[David S. Miller]

   From: Jakub Jelinek <jakub@redhat.com>
   Date: Fri, 5 Apr 2002 10:23:03 -0500

   > This is likely to confuse not only GDB, as any Sparc backtrace
   > mechanism is going to fall victim to this.
   
   Wouldn't it be better to really check if the last real instruction
   (or dbr sequence) is a call? I'm afraid you'll emit nop even for
   func1:
       ...
       b .L123
        do_something
   func2:

You could add that check, but I preferred this obvious fix for the 3.1
branch.