configure: lookup meson exutable from PATH

Upstream-Status: Inappropriate [workaround, would need a real fix for upstream]

Author: hundeboll

configure

@@ -983,12 +983,7 @@ mkvenv="$python ${source_path}/python/scripts/mkvenv.py"
 $mkvenv ensuregroup --dir "${source_path}/python/wheels" \
      ${source_path}/pythondeps.toml meson || exit 1
 
-# At this point, we expect Meson to be installed and available.
-# We expect mkvenv or pip to have created pyvenv/bin/meson for us.
-# We ignore PATH completely here: we want to use the venv's Meson
-# *exclusively*.
-
-meson="$(cd pyvenv/bin; pwd)/meson"
+meson=`which meson`
 
 # Conditionally ensure Sphinx is installed.