configure: set the meson executable suffix/ext

The 'rustfmt' target runs meson: it needs the correct path with
extension on Windows.

Signed-off-by: Marc-André Lureau <marcandre.lureau@redhat.com>
Reviewed-by: Daniel P. Berrangé <berrange@redhat.com>
Message-ID: <20250924120426.2158655-20-marcandre.lureau@redhat.com>

configure

@@ -1000,7 +1000,19 @@ $mkvenv ensuregroup --dir "${source_path}/python/wheels" \
 # We ignore PATH completely here: we want to use the venv's Meson
 # *exclusively*.
 
-meson="$(cd pyvenv/bin; pwd)/meson"
+# for msys2
+get_pwd() {
+    if pwd -W >/dev/null 2>&1; then
+        pwd -W
+    else
+        pwd
+    fi
+}
+
+meson="$(cd pyvenv/bin; get_pwd)/meson"
+if [ -f "$meson$EXESUF" ]; then
+  meson="$meson$EXESUF"
+fi
 
 # Conditionally ensure Sphinx is installed.