build_target_util: Rename to build_target_lib.

Nitty name change. The module contains a class and is in lib, so
should be a _lib, not a _util.

BUG=chromium:1060351
TEST=run_tests

Change-Id: I539dc8e5288e71cc9408bc68861f20579ac70937
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/chromite/+/2095746
Commit-Queue: Alex Klein <saklein@chromium.org>
Tested-by: Alex Klein <saklein@chromium.org>
Reviewed-by: Mike Frysinger <vapier@chromium.org>
diff --git a/api/controller/packages.py b/api/controller/packages.py
index 541e715..201303c 100644
--- a/api/controller/packages.py
+++ b/api/controller/packages.py
@@ -14,7 +14,7 @@
 from chromite.api.controller import controller_util
 from chromite.api.gen.chromite.api import binhost_pb2
 from chromite.api.gen.chromiumos import common_pb2
-from chromite.lib import build_target_util
+from chromite.lib import build_target_lib
 from chromite.lib import constants
 from chromite.lib import cros_build_lib
 from chromite.lib import cros_logging as logging
@@ -44,7 +44,7 @@
 def Uprev(input_proto, output_proto, _config):
   """Uprev all cros workon ebuilds that have changes."""
   target_names = [t.name for t in input_proto.build_targets]
-  build_targets = [build_target_util.BuildTarget(t) for t in target_names]
+  build_targets = [build_target_lib.BuildTarget(t) for t in target_names]
   overlay_type = _OVERLAY_TYPE_TO_NAME[input_proto.overlay_type]
   chroot = controller_util.ParseChroot(input_proto.chroot)
   output_dir = input_proto.output_dir or None