Workaround for broken implicit import auto static linking

Author: kateinoigakukun

test/lit.cfg

@@ -1511,6 +1511,13 @@ elif run_os == 'wasi':
         '-target', config.variant_triple,
         '-Xcc', '--sysroot=%s' % config.variant_sdk,
         '-Xclang-linker', '--sysroot=%s' % config.variant_sdk,
+        # workaroud: Even though StdlibUnittest uses _Concurrency,
+        # _Concurrency module won't be listed in IMPORTED_MODULE.
+        # And -parse-stdlib disables implicit imports, so autolink
+        # system is broken when static link & -parse-stdlib & importing _Concurrency.
+        # This issue causes link failure that reports there are missing swift_task_XX
+        # symbols.
+        '-lswift_Concurrency',
         '-toolchain-stdlib-rpath', resource_dir_opt, 
         mcp_opt, config.swift_test_options,
         config.swift_driver_test_options, swift_execution_tests_extra_flags])