openjdk: add pkgconfig support

pkgconfig is now enabled, so that pkg-config
macros will not fail in configure stage.

Signed-off-by: Cristian Iorga <cristian.iorga@intel.com>
ecj: fix unpackpost task

ecj recipe is built as initial and as native,
as such, unpackpost is run multiple times over
the same code source. Added check if a move
operation hasn't been already executed.

Signed-off-by: Cristian Iorga <cristian.iorga@intel.com>