Remove SourceFileGenerator check and stubs

They're not used, and we're adding a function to the SourceFileGenerator
interface.

Bug: 73745773
Test: diff out/soong/build.ninja
Test: diff out/soong/Android-aosp_arm.mk
Test: rm -rf out; m
Change-Id: Ie8de085212778ee2a164e376b04ab3fe003afc86
diff --git a/build/hidl_interface.go b/build/hidl_interface.go
index 16ac03b..396cf67 100644
--- a/build/hidl_interface.go
+++ b/build/hidl_interface.go
@@ -73,8 +73,6 @@
 	properties hidlInterfaceProperties
 }
 
-var _ genrule.SourceFileGenerator = (*hidlInterface)(nil)
-
 func processSources(mctx android.LoadHookContext, srcs []string) ([]string, []string, bool) {
 	var interfaces []string
 	var types []string // hidl-gen only supports types.hal, but don't assume that here
@@ -402,12 +400,6 @@
 }
 func (h *hidlInterface) DepsMutator(ctx android.BottomUpMutatorContext) {
 }
-func (h *hidlInterface) GeneratedHeaderDirs() android.Paths {
-	return []android.Path{}
-}
-func (h *hidlInterface) GeneratedSourceFiles() android.Paths {
-	return []android.Path{}
-}
 
 var hidlInterfaceMutex sync.Mutex
 var hidlInterfaces []*hidlInterface
diff --git a/build/hidl_package_root.go b/build/hidl_package_root.go
index 15c63f3..1f68af4 100644
--- a/build/hidl_package_root.go
+++ b/build/hidl_package_root.go
@@ -18,7 +18,6 @@
 	"sync"
 
 	"android/soong/android"
-	"android/soong/genrule"
 )
 
 func init() {
@@ -34,18 +33,10 @@
 	}
 }
 
-var _ genrule.SourceFileGenerator = (*hidlPackageRoot)(nil)
-
 func (r *hidlPackageRoot) GenerateAndroidBuildActions(ctx android.ModuleContext) {
 }
 func (r *hidlPackageRoot) DepsMutator(ctx android.BottomUpMutatorContext) {
 }
-func (r *hidlPackageRoot) GeneratedHeaderDirs() android.Paths {
-	return []android.Path{}
-}
-func (r *hidlPackageRoot) GeneratedSourceFiles() android.Paths {
-	return []android.Path{}
-}
 
 var packageRootsMutex sync.Mutex
 var packageRoots []*hidlPackageRoot