cc bazel handlers: use better interface checking

This is a far better approach for ensuring that bazel handlers implement
the BazelHandler interface, as it causes a compile error if they do not
implement the appropriate interface methods.

Test: Manually verified no change in ninja file
Change-Id: I63a4f8b57e3aedd4c0915c2fd2eb7029e9a993aa

cc/library.go

@@ -642,11 +642,11 @@ type libraryDecorator struct {
 }
 
 type ccLibraryBazelHandler struct {
-	BazelHandler
-
 	module *Module
 }
 
+var _ BazelHandler = (*ccLibraryBazelHandler)(nil)
+
 // generateStaticBazelBuildActions constructs the StaticLibraryInfo Soong
 // provider from a Bazel shared library's CcInfo provider.
 func (handler *ccLibraryBazelHandler) generateStaticBazelBuildActions(ctx android.ModuleContext, label string, ccInfo cquery.CcInfo) {