stringify placeholder entries before adding them to the command line

Summary: `placeholders` don't have to be strings, but `cmd_args` expects us to add a string. So, call `str` on everything that we add.

Reviewed By: navidqar

Differential Revision: D51305891

fbshipit-source-id: 41c7a31631908f3e689ce5a82f6883d8685a7308

prelude/android/android_manifest.bzl

@@ -56,7 +56,7 @@ def generate_android_manifest(
 
     placeholder_entries_args = cmd_args()
     for key, val in placeholder_entries.items():
-        placeholder_entries_args.add(cmd_args(key, val, delimiter = " "))
+        placeholder_entries_args.add(cmd_args(str(key), str(val), delimiter = " "))
     placeholder_entries_file = ctx.actions.write("{}/placeholder_entries_file".format(module_name), placeholder_entries_args)
 
     generate_manifest_cmd.add(["--placeholder-entries-list", placeholder_entries_file])