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
diff --git a/cc/ndk_library.go b/cc/ndk_library.go
index 066fb98..c517523 100644
--- a/cc/ndk_library.go
+++ b/cc/ndk_library.go
@@ -258,8 +258,8 @@
 	return flags
 }
 
-func (stub *stubDecorator) compilerFlags(ctx ModuleContext, flags Flags) Flags {
-	flags = stub.baseCompiler.compilerFlags(ctx, flags)
+func (stub *stubDecorator) compilerFlags(ctx ModuleContext, flags Flags, deps PathDeps) Flags {
+	flags = stub.baseCompiler.compilerFlags(ctx, flags, deps)
 	return addStubLibraryCompilerFlags(flags)
 }