Handle product vars *flags props in cc* modules

Test: build/bazel/ci/bp2build.sh
Bug: 188497994
Change-Id: Ifb379e370075d6a7bc55b82d79c210c31ef377e9
diff --git a/bp2build/cc_object_conversion_test.go b/bp2build/cc_object_conversion_test.go
index f7e94c2..57f75ea 100644
--- a/bp2build/cc_object_conversion_test.go
+++ b/bp2build/cc_object_conversion_test.go
@@ -210,7 +210,7 @@
 		expectedBazelTargets: []string{`cc_object(
     name = "foo",
     asflags = select({
-        "//build/bazel/product_variables:platform_sdk_version": ["-DPLATFORM_SDK_VERSION={Platform_sdk_version}"],
+        "//build/bazel/product_variables:platform_sdk_version": ["-DPLATFORM_SDK_VERSION=$(Platform_sdk_version)"],
         "//conditions:default": [],
     }),
     copts = ["-fno-addrsig"],