Go: Disable libartd by default

Free up some space in userdebug to make consistent with user. Go
doesn't have enough resources, really, anyways.

Frees up about 9M.

Bug: 62087184
Test: lunch gobo-userdebug && m && ls $OUT/system/lib/libartd*
Change-Id: I109bbbc59b71de48ca63ba64142148a50fb0af55