Merge r6130:

- AIX implementations of various stuff, nothing surprising.

- For all platforms: make VG_(read) and VG_(write) return (negative)
  actual error values rather than producing -1 for all failures.



git-svn-id: svn://svn.valgrind.org/valgrind/trunk@6267 a5019735-40e9-0310-863c-91ae7b9d1cf9
diff --git a/include/pub_tool_libcfile.h b/include/pub_tool_libcfile.h
index eb824fe..bb371b9 100644
--- a/include/pub_tool_libcfile.h
+++ b/include/pub_tool_libcfile.h
@@ -35,6 +35,8 @@
    File-related functions.
    ------------------------------------------------------------------ */
 
+/* To use this file you must first include pub_tool_vki.h. */
+
 extern SysRes VG_(open)   ( const Char* pathname, Int flags, Int mode );
 extern void   VG_(close)  ( Int fd );
 extern Int    VG_(read)   ( Int fd, void* buf, Int count);