libXrandr: Update version from 1.4.2 to 1.5.1

Version 1.5.0 adds support for monitor objects, needed for tiled
displays, that means displays with more than one panel (MST,
Multi-Stream Transport) like the Dell UP3214Q [1].

Announcement [1]:

> Add support for monitors and fixes requires on libX11.
>
> Keith Packard (2):
>       libXrandr: Clean up compiler warnings
>       Add monitors, update to version 1.5 (v2)
>
> Michael Joost (1):
>       Remove fallback for _XEatDataWords, require libX11 1.6 for it

[1] https://en.wikipedia.org/wiki/DisplayPort#Multiple_displays_on_single_DisplayPort_connector
[2] https://lists.x.org/archives/xorg-announce/2015-May/002606.html

libXrandr.be0

@@ -1,6 +1,6 @@
 #!/usr/bin/env beesh
 
-# BEE_VERSION libXrandr-1.4.2-0
+# BEE_VERSION libXrandr-1.5.1-0
 
 ## this file was created by bee init and should be executed to build a
 ## bee-package. (Additional hints are located at the end of this file.)