Move policy subdirectory into package directory

Go's tooling expects that all files in the same package are in the
same directory.  Move the policy/*.go files to policy_*.go.

Test: go test ./...
Change-Id: I7e81936ddd20a5ffb4770ae23bdb6e411d6924cc

tools/compliance/policy_resolveshare.go

@@ -0,0 +1,21 @@
+// Copyright 2021 Google LLC
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//      http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package compliance
+
+// ResolveSourceSharing implements the policy for source-sharing.
+func ResolveSourceSharing(lg *LicenseGraph) ResolutionSet {
+	ResolveTopDownConditions(lg)
+	return WalkResolutionsForCondition(lg, ImpliesShared)
+}