dselect: Do not leak keybindings from describenext()

The code affected is currently unused.

Warned-by: coverity

debian/changelog

@@ -8,6 +8,7 @@ dpkg (1.17.9) UNRELEASED; urgency=low
   * Do not leak the filepackages iterator when a directory is used by other
     packages.
   * Fix short lived memory leaks in «dpkg-split --split».
+  * Fix memory leak in unused Keybindings screen in dselect.
 
   [ Updated scripts translations ]
   * French (Steve Petruzzello). Closes: #746350

dselect/baselist.cc

@@ -272,6 +272,7 @@ void baselist::itd_keys() {
     if (x >= givek) y++;
     mvwaddstr(infopad, y,givek, ta[0]);
     waddch(infopad,'\n');
+    delete [] ta;
   }
 }