Build release versions by default (again)

This turned out to be why all the release users are on the devbuild now. So far I presumed that the release build process would set res/bools.xml:def_release to true, while in reality the devbuild build process sets it to false.

Thus, def_release needs to be true by default, but it was (possibly accidentally) set to false here:
https://hg.adblockplus.org/adblockplusandroid/rev/58a55e3b9974

So all this patch does is set it back to true. The next release we publish will actually consider itself a release build.

[Wladimir Palant, 2014-03-03 07:41:37]

Ouch... LGTM