switch aio and shm to do_mmap_pgoff(), make do_mmap() static

after all, 0 bytes and 0 pages is the same thing...

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
diff --git a/include/linux/mm.h b/include/linux/mm.h
index 7d5c37f..4189e0d 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -1394,7 +1394,7 @@
 extern unsigned long mmap_region(struct file *file, unsigned long addr,
 	unsigned long len, unsigned long flags,
 	vm_flags_t vm_flags, unsigned long pgoff);
-extern unsigned long do_mmap(struct file *, unsigned long,
+extern unsigned long do_mmap_pgoff(struct file *, unsigned long,
         unsigned long, unsigned long,
         unsigned long, unsigned long);
 extern int do_munmap(struct mm_struct *, unsigned long, size_t);