Fix using aidl files from filegroups

Compute sources including from filegroup and genrule dependencies
before determining if any sources will cause flags to be added.

Test: gen_test.go
Change-Id: I0434b003bbda07a58bb2ce1a0a72997918c8fae2

cc/llndk_library.go

@@ -70,8 +70,8 @@ type llndkStubDecorator struct {
 	versionScriptPath      android.ModuleGenPath
 }
 
-func (stub *llndkStubDecorator) compilerFlags(ctx ModuleContext, flags Flags) Flags {
-	flags = stub.baseCompiler.compilerFlags(ctx, flags)
+func (stub *llndkStubDecorator) compilerFlags(ctx ModuleContext, flags Flags, deps PathDeps) Flags {
+	flags = stub.baseCompiler.compilerFlags(ctx, flags, deps)
 	return addStubLibraryCompilerFlags(flags)
 }