Add BIONIC_COMPLICATED_NULLNESS as _Null_unspecified

In some cases, the nullability of the pointer argument is too
complicated. Developers have better check relevant manuals or
code before annotating.

Bugs: b/245972273
Test: None
Change-Id: I3589a5080b267d1766cc8ed99868129ac16e4012
diff --git a/libc/include/fcntl.h b/libc/include/fcntl.h
index 4ef894b..1ec932b 100644
--- a/libc/include/fcntl.h
+++ b/libc/include/fcntl.h
@@ -149,7 +149,7 @@
  *
  * Available since API level 21.
  */
-ssize_t splice(int __in_fd, off64_t* _Null_unspecified __in_offset, int __out_fd, off64_t* _Null_unspecified __out_offset, size_t __length, unsigned int __flags) __INTRODUCED_IN(21);
+ssize_t splice(int __in_fd, off64_t* __BIONIC_COMPLICATED_NULLNESS __in_offset, int __out_fd, off64_t* __BIONIC_COMPLICATED_NULLNESS __out_offset, size_t __length, unsigned int __flags) __INTRODUCED_IN(21);
 
 /**
  * [tee(2)](http://man7.org/linux/man-pages/man2/tee.2.html)