Patch to fix build with Qt 5.5, taken from upstream:
   https://github.com/lxde/liblxqt/commit/7303ea207de0771d6f450a31ec4a1ce69202869b

diff -u -r liblxqt-0.9.0.orig/lxqtnotification.h liblxqt-0.9.0/lxqtnotification.h
--- liblxqt-0.9.0.orig/lxqtnotification.h	2015-07-27 22:49:05.365166482 +0200
+++ liblxqt-0.9.0/lxqtnotification.h	2015-07-27 22:49:36.897606619 +0200
@@ -25,6 +25,7 @@
 #ifndef LXQTNOTIFICATION_H
 #define LXQTNOTIFICATION_H
 
+#include <QObject>
 #include <QStringList>
 #include "lxqtglobals.h"
 
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<tr><td><span title='2020-06-27 23:42:20 +0200'>2020-06-27</span></td><td><a href='/guix/commit/nix/libutil/hash.hh?id=8e6c1415d87272c0221ce328715fc0dd1dd3e032'>daemon: Recognize SHA3 and BLAKE2s.</a><span class='msg-avail'>...<span class='msg-tooltip'>* nix/libutil/hash.hh (HashType): Add htSHA3_256, htSHA3_512, and
htBLAKE2s_256.
* nix/libutil/hash.cc (parseHashType, printHashType): Recognize them.
* tests/store.scm ("add-to-store"): Test these algorithms.
</span></span></td><td>Ludovic Courtès</td></tr>
<tr><td><span title='2020-06-27 23:42:20 +0200'>2020-06-27</span></td><td><a href='/guix/commit/nix/libutil/hash.hh?id=3fb6b8f30444d41963ba5bdd441123a6d2df17bd'>daemon: Map directly to gcrypt hash functions.</a><span class='msg-avail'>...<span class='msg-tooltip'>* nix/libutil/hash.hh (HashType): Map directly to GCRY_MD_ values.
(md5HashSize, sha1HashSize, sha256HashSize, sha512HashSize): Remove.
* nix/libutil/hash.cc (Hash::Hash): Use 'gcry_md_get_algo_dlen'.
</span></span></td><td>Ludovic Courtès</td></tr>