convert to SLOT-ed libbase

This includes a couple of fixes:
 - import latest common.mk (for its flag handling updates)
 - use pkg-config to find things
 - build against SLOT-ed libbase

BUG=chromium-os:16623
TEST=`emerge-x86-alex cros_boot_mode` still works
TEST=`cros_run_unit_tests --board x86-alex -p cros_boot_mode` passes

Change-Id: I677650e0160cb3a40496934adc405e8fea0ee601
Reviewed-on: https://gerrit.chromium.org/gerrit/17716
Reviewed-by: Will Drewry <wad@chromium.org>
Commit-Ready: Mike Frysinger <vapier@chromium.org>
Tested-by: Mike Frysinger <vapier@chromium.org>
2 files changed