When searching for an old entry to reuse when updating an existing
symbol list, take into account the symbol's argument list not to
always match the same entry for overloaded symbols.

Closes #3406644.

git-svn-id: https://geany.svn.sourceforge.net/svnroot/geany/trunk@5910 ea778897-0a13-0410-b9d1-a72fbfd435f5