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/sysroot.py b/api/controller/sysroot.py
index 859c779..3615078 100644
--- a/api/controller/sysroot.py
+++ b/api/controller/sysroot.py
@@ -15,7 +15,7 @@
 from chromite.api import validate
 from chromite.api.controller import controller_util
 from chromite.api.metrics import deserialize_metrics_log
-from chromite.lib import build_target_util
+from chromite.lib import build_target_lib
 from chromite.lib import cros_build_lib
 from chromite.lib import cros_logging as logging
 from chromite.lib import goma_lib
@@ -43,8 +43,8 @@
   build_target_name = input_proto.build_target.name
   profile = input_proto.profile.name or None
 
-  build_target = build_target_util.BuildTarget(name=build_target_name,
-                                               profile=profile)
+  build_target = build_target_lib.BuildTarget(name=build_target_name,
+                                              profile=profile)
   run_configs = sysroot.SetupBoardRunConfig(
       force=replace_sysroot, upgrade_chroot=update_chroot)
 
@@ -123,7 +123,7 @@
   sysroot_path = input_proto.sysroot.path
   build_target_name = input_proto.sysroot.build_target.name
 
-  build_target = build_target_util.BuildTarget(name=build_target_name)
+  build_target = build_target_lib.BuildTarget(name=build_target_name)
   target_sysroot = sysroot_lib.Sysroot(sysroot_path)
   run_configs = sysroot.SetupBoardRunConfig(usepkg=not compile_source)