liblockfile: set default mailgroup and install libnfslock

* Set the default mailgroup to 'mail' or it will use 'root'.
* Set --with-libnfslock so it builds and install libnfslock.
* The patch is to fix nfslib build failure and add missing soname lib.
* No need to override the do_install, set EXTRA_OEMAKE instead.

Signed-off-by: Jackie Huang <jackie.huang@windriver.com>
Signed-off-by: Martin Jansa <Martin.Jansa@gmail.com>