Generate tidy-* rules unless tidy is disabled

* make tidy-soong_subset, or make tidy-<any_directory>,
  should trigger the same clang-tidy compilations
  with or without global WITH_TIDY=1.
* Normal make should not trigger clang-tidy compilations
  unless global WITH_TIDY=1 or a module has set tidy:true.

Bug: 213918926
Test: NINJA_ARGS="-n" make tidy-soong_subset
Test: NINJA_ARGS="-n" make <some-library>
Change-Id: Iafffd3894abe137c9584c2c01830898422f9a677

cc/util.go

@@ -85,6 +85,7 @@ func flagsToBuilderFlags(in Flags) builderFlags {
 		toolchain:     in.Toolchain,
 		gcovCoverage:  in.GcovCoverage,
 		tidy:          in.Tidy,
+		needTidyFiles: in.NeedTidyFiles,
 		sAbiDump:      in.SAbiDump,
 		emitXrefs:     in.EmitXrefs,