[SPARC64]: Fix put_user() calls in binfmt_aout32.c

argv and envp are pointers to u32's in userspace, so don't
try to put_user() a NULL to them.

Aparently gcc-4.2.x now warns about this, and since we use
-Werror for arch/sparc64 code, this breaks the build.
Signed-off-by: David S. Miller <davem@davemloft.net>

arch/sparc64/kernel/binfmt_aout32.c

@@ -177,7 +177,7 @@ static u32 __user *create_aout32_tables(char __user *p, struct linux_binprm *bpr
 			get_user(c,p++);
 		} while (c);
 	}
-	put_user(NULL,argv);
+	put_user(0,argv);
 	current->mm->arg_end = current->mm->env_start = (unsigned long) p;
 	while (envc-->0) {
 		char c;
@@ -186,7 +186,7 @@ static u32 __user *create_aout32_tables(char __user *p, struct linux_binprm *bpr
 			get_user(c,p++);
 		} while (c);
 	}
-	put_user(NULL,envp);
+	put_user(0,envp);
 	current->mm->env_end = (unsigned long) p;
 	return sp;
 }