configure: Fix libxml2 development library dependency checking

The commit that added libxml2 support didn't fully check for the libxml2
development script in the Asterisk configure file. As a result, Asterisk could
be configured, then fail on menuselect. This patch fixes it so that Asterisk
should detect the libxml2 dependency failure first.


git-svn-id: http://svn.asterisk.org/svn/asterisk/trunk@418850 f38db490-d61c-443f-a65b-d21fe96a405b
Add svn:ignore property

git-svn-id: http://svn.asterisk.org/svn/asterisk/trunk@418851 f38db490-d61c-443f-a65b-d21fe96a405b