The www/apache22 port has support for multiple profiles which are controlled from
a single rc.d script.  However, in some instances multiple profiles share a common
base configuration or only differ by a few directives.  This patch adds support
for a new rc.conf flag, apache22_profile_directives, which when set adds an
additional directive to the command line specifying the name of the profile itself.

Consider the following example:

apache22_enable="YES"
apache22_profiles="httpd mail"
apache22_httpd_configfile="/usr/local/etc/apache22/httpd.manhattan.conf"
apache22_mail_configfile="/usr/local/etc/apache22/httpd.mail.conf"

The two configuration files only differ in a few places that define the Listen
address and ServerName, plus a Directory directive or two.  Due to the small
number of differences, these files could be collapsed in to one which
simplifies global level changes.

Consider the following modified example:

<IfDefine profile_httpd>
  Listen manhattan.downtools.com.au:80
  ServerName manhattan.downtools.com.au
  DocumentRoot /home/htdocs/default/data
</IfDefine>
<IfDefine profile_mail>
  Listen mail.downtools.com.au:443
  ServerName mail.downtools.com.au
  DocumentRoot /home/htdocs/mail/data
</IfDefine>

...

<IfDefine profile_mail>
  <Directory /usr/local/www/roundcube>
    ...
    SSLRequireSSL
  </Directory>
</IfDefine>

By collapsing the minor differences, both profiles can still be controlled
individually via the rc.d script as a -Dprofile_${profile} flag will be added
to the command line for each.  This results in a slightly simplified rc.conf
configuration and less duplication.

apache22_enable="YES"
apache22_profiles="httpd mail"
apache22_profile_directives="YES"
apache22_httpd_configfile="/usr/local/etc/apache22/httpd.manhattan.conf"
apache22_mail_configfile="${apache22_httpd_configfile}"