message: special case error output when pkg-config is not installed
diff: @@ -223,7 +223,12 @@ fn main() {
  .expect("Can't copy bindings to output directory");
  } else {
  if let Err(pkg_config_err) = &gdal_pkg_config {
  + // Special case output for this common error
  + if matches!(pkg_config_err, pkg_config::Error::Command { cause, .. } if cause.kind() == std::io::ErrorKind::NotFound) {
  + panic!("Could not find `pkg-config` in your path. Please install it before building gdal-sys.");
  + } else {
  panic!("Error while running `pkg-config`: {}", pkg_config_err);
  + }
  } else {
  panic!("No GDAL version detected");
  }
  