Previously, we left out the dependency of the QSTR header on
modules.h. This was done to prevent rebuilds of the entire
MicroPython sources whenever a Pycardium module is changed. This
leads to issues where QSTRs got out of sync and weird errors like
the following could happen:
import foo_moduleException: No module `abc_def` (a different string than expected)
Attempt to fix this by only updating the QSTR header when the
module-header actually changes. For this, a few workarounds are needed:
Replace symlinks with actual copied files so timestamps change on
updates.
Add a hack so meson picks up on the dependency of the file in genhdr/
