Fix meson executable

• on my system meson is a link to python-exec2

  $ ls -ld $(which meson)
  /usr/bin/meson -> ../lib/python-exec/python-exec2

  The python2-exec must not be executed directly.
• Currently the mesonExecutable is canonicalized, which also resolves symlinks. This causes the meson plugin to execute stuff like:

  $ python-exec2 --reconfigure

  instead of

  $ meson --reconfigure

  Fix this by not canonicalizing the mesonExecutable, validity is already checked earlier.

BUG: 412477

FIXED-IN: 5.8.220400