OQGraph should be disabled for POWER8 Ubuntu package builds

On POWER8, the libjudydebian1 package is empty except for the copyright and changelog files:

u0016471@sys-74005:~$ dpkg -L libjudydebian1

/.

/usr

/usr/lib

/usr/share

/usr/share/doc

/usr/share/doc/libjudydebian1

/usr/share/doc/libjudydebian1/copyright

/usr/share/doc/libjudydebian1/changelog.Debian.gz

This leads to issues when compiling:

• If the libjudydebian1 and libjudy-dev packages are not installed, building MariaDB fails with the following failure:

  dpkg-checkbuilddeps: Unmet build dependencies: libjudy-dev

  dpkg-buildpackage: warning: build dependencies/conflicts unsatisfied; aborting

Log: http://buildbot.askmonty.org/buildbot/builders/p8-trusty-deb/builds/616/steps/compile/logs/stdio

• If the two packages are installed, building MariaDB fails with the following failure:

make[3]: *** No rule to make target `/usr/lib/libJudy.so', needed by `storage/oqgraph/ha_oqgraph.so'.  Stop.

Log: http://buildbot.askmonty.org/buildbot/builders/p8-trusty-deb/builds/615/steps/compile/logs/stdio

We should disable building OQGraph on POWER8 and remove the dependency on the libjudy-dev package, at least until the libjudydebian1 package gets fixed upstream.