bind: Update libxml2 check to make it deterministic.
* Firstly configure scritp was testing files from bin folder.
In our case we don't copy bin folder to sysroot for target
recipes. So added extra check to validate .pc file from lib
folder via a patch to configure.in file.
* Secondly linxml2 dependency was missing. So added PACKAGECONFIG
for libxml2.
Signed-off-by: Noor Ahsan <noor_ahsan@mentor.com> Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>
