Set output for build_prop even on Soong only build

Without this change, Soong only build may break unexpectedly if some
modules refer to the build_prop module.

Bug: 322090587
Test: soong only build
Change-Id: I7571bdf0aa6c08ade8f130842c84c02bb0233acb

android/build_prop.go

@@ -60,6 +60,7 @@ func (p *buildPropModule) GenerateAndroidBuildActions(ctx ModuleContext) {
 	p.outputFilePath = PathForModuleOut(ctx, "build.prop").OutputPath
 	if !ctx.Config().KatiEnabled() {
 		WriteFileRule(ctx, p.outputFilePath, "# no build.prop if kati is disabled")
+		ctx.SetOutputFiles(Paths{p.outputFilePath}, "")
 		return
 	}