debian/changelog: specify the bug report that this version should close, but...

debian/changelog: specify the bug report that this version should close, but not closing the bug as asked by the reporter.

debian/changelog

 massxpert (3.5.0-1) unstable; urgency=medium
 
-  * New upstream version 3.5.0 with finished Qt5 port.
+  * Fixes to the code errors spotted by gcc-5.1.1 (20150622). Not closing
+    the bug number #777998 as requested by the reporter (Matthias Klose
+    <doko@debian.org>);
+
+  * New upstream version 3.5.0 with finished Qt5 port;
 
   * Build-Depends: change to qtbase5-dev (>= 5.3.2+dfsg-5), libqt5svg5-dev
-    (>= 5.3.2-2), and cmake (>= 3.2.2-2)
+    (>= 5.3.2-2), and cmake (>= 3.2.2-2);
 
-  * Standards-Version: bump up to 3.9.6. No changes needed.
+  * Standards-Version: bump up to 3.9.6. No changes needed;
 
   * moved upstream to upstream/metadata (Thanks Andreas Tille, although I
     had done this long ago, Mon Aug 18, without pushing, sadly).