Partial fix for 0005207: Improve performance of "My View"

Added an index on bug_id on the bug notes table. This should improve the speed of the view issues page.

git-svn-id: http://mantisbt.svn.sourceforge.net/svnroot/mantisbt/trunk@3444 <a class="text" href="/?p=mantisbt.git;a=object;h=f5dc347c">f5dc347c</a>-c33d-0410-90a0-b07cc1902cb9