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
diff --git a/cc/compiler.go b/cc/compiler.go
index 8adc3ab..9dbf2d1 100644
--- a/cc/compiler.go
+++ b/cc/compiler.go
@@ -675,7 +675,7 @@
 }
 
 // Compile a list of source files into objects a specified subdirectory
-func compileObjs(ctx android.ModuleContext, flags builderFlags, subdir string,
+func compileObjs(ctx ModuleContext, flags builderFlags, subdir string,
 	srcFiles, noTidySrcs, pathDeps android.Paths, cFlagsDeps android.Paths) Objects {
 
 	return transformSourceToObj(ctx, subdir, srcFiles, noTidySrcs, flags, pathDeps, cFlagsDeps)