Revert "Remove -f x flag from mcrun command"

This reverts commit aa26177.

Author: jplexer

pebble_tool/commands/sdk/project/build.py

@@ -142,6 +142,7 @@ def run_moddable_prebuild(self):
                 cmd = [
                     'mcrun',
                     '-m', './src/embeddedjs/manifest.json',
+                    '-f', 'x',
                     '-p', f'pebble/{platform}',
                     '-t', 'build',
                     '-o', mcrun_output_dir,