rust: add darwin as host arch

Bug: 169739272
Test: m nothing
Change-Id: I3ef2a3dd7e80b9fe47edb6eb04ed9d37e8d58096
diff --git a/rust/project_json_test.go b/rust/project_json_test.go
index 8c1c436..11964f3 100644
--- a/rust/project_json_test.go
+++ b/rust/project_json_test.go
@@ -139,10 +139,11 @@
 			t.Fatalf("Unexpected type for root_module: %v", crate["root_module"])
 		}
 		if strings.Contains(rootModule, "libbindings1") && !strings.Contains(rootModule, "android_arm64") {
-			t.Errorf("The source for libbindings1 does not contain android_arm64, got %v", rootModule)
+			t.Errorf("The source path for libbindings1 does not contain android_arm64, got %v", rootModule)
 		}
-		if strings.Contains(rootModule, "libbindings2") && !strings.Contains(rootModule, "linux_glibc") {
-			t.Errorf("The source for libbindings2 does not contain linux_glibc, got %v", rootModule)
+		if strings.Contains(rootModule, "libbindings2") && !strings.Contains(rootModule, android.BuildOs.String()) {
+			t.Errorf("The source path for libbindings2 does not contain the BuildOs, got %v; want %v",
+				rootModule, android.BuildOs.String())
 		}
 	}
 }