Website tablecg fix

[Justin C. Sherrill]

I goofed on the body content table; pages with text that takes less vertical
space than the now-longer side menu will end up centered in the larger
table cell, meaning the content will visually shift up and down between
pages.  It's an easy change to tablecg.c.

Here's the diff:
http://home.shiningsilence.com:81/tablecg3.diff

Compare these pages to see what changes:

http://www.dragonflybsd.org/Main/index.cgi
http://home.shiningsilence.com:81/Main/index.cgi

http://www.dragonflybsd.org/Main/bugs.cgi
http://home.shiningsilence.com:81/Main/bugs.cgi

http://www.dragonflybsd.org/Goals/index.cgi
http://home.shiningsilence.com:81/Goals/index.cgi