Darwin uses DYLD_LIBRARY_PATH, not LD_LIBRARY_PATH

--- meson.build.orig
+++ meson.build
@@ -574,7 +574,7 @@
 tests_environment.set('GJS_DEBUG_OUTPUT', 'stderr')
 tests_environment.prepend('GI_TYPELIB_PATH', meson.current_build_dir(),
     js_tests_builddir, libgjs_test_tools_builddir)
-tests_environment.prepend('LD_LIBRARY_PATH', meson.current_build_dir(),
+tests_environment.prepend('DYLD_LIBRARY_PATH', meson.current_build_dir(),
     js_tests_builddir, libgjs_test_tools_builddir)
 tests_environment.set('G_FILENAME_ENCODING', 'latin1')
 # Workaround for https://github.com/google/sanitizers/issues/1322