Export variant/features via soong_injection

Test: build/bazel/ci/bp2build.sh
Change-Id: If70043dc9d020d5f4a243ba4b192b99c9c7e8563
diff --git a/bp2build/conversion_test.go b/bp2build/conversion_test.go
index 629ca9b..c94a923 100644
--- a/bp2build/conversion_test.go
+++ b/bp2build/conversion_test.go
@@ -103,6 +103,10 @@
 			basename: "soong_config_variables.bzl",
 		},
 		{
+			dir:      "product_config",
+			basename: "arch_configuration.bzl",
+		},
+		{
 			dir:      "api_levels",
 			basename: GeneratedBuildFileName,
 		},