bufr: use f2py build directory outside /tmp

[mathomp4]

Summary

With +python and Python 3.12 or newer, NumPy f2py uses Meson to build BUFR's Python extension. By default, f2py creates its build directory with Python's temporary-directory mechanism. On systems where /tmp is mounted noexec, Meson then cannot execute its compiler sanity-check program.

meson.build:1:0: ERROR: Could not invoke sanity check executable:
[Errno 13] Permission denied:
'/tmp/.../meson-private/sanity_check_for_fortran.exe'

Pass f2py's --build-dir option from BUFR's CMake custom command, placing the temporary Meson project under CMake's binary directory instead of /tmp.

The change is limited to bufr+python ^python@3.12:, matching the f2py versions that use Meson.

Testing

Successfully built on Linux:

bufr@12.3.0+python ^python@3.13 %gcc@15.2.0

Before this change, f2py invoked Meson from /tmp and failed on its Fortran sanity check. With this change, BUFR builds successfully.

AI assistance disclosure

GPT-5.6 assisted with identifying the f2py/Meson failure and drafting the package change. The change was reviewed and tested by the submitter.

[mathomp4]

Note to @climbfuji: This was found in my test builds of my spack-stack testing. Fun with noexec!

[mathomp4]

Converting to draft. Something isn't quite right. Still seeing a bufr build failure...though I thought it worked? Weird...

[mathomp4]

Okay. Should be good to go. I really hate f2py sometimes.