chore(build): only execute lua multi-threading tests when on cygwin or linux, and using g++

Signed-off-by: Leonardo de Moura <leonardo@microsoft.com>

src/shell/lua/CMakeLists.txt

@@ -3,3 +3,11 @@ target_link_libraries(leanlua ${EXTRA_LIBS})
 add_test(NAME leanluatests
          WORKING_DIRECTORY "${LEAN_SOURCE_DIR}/../tests/lua"
          COMMAND "./test.sh" "${CMAKE_CURRENT_BINARY_DIR}/leanlua")
+
+if((${CYGWIN} EQUAL "1") OR (${CMAKE_SYSTEM_NAME} MATCHES "Linux"))
+  if (NOT (${CMAKE_CXX_COMPILER} MATCHES "clang"))
+    add_test(NAME leanluathreadtests
+      WORKING_DIRECTORY "${LEAN_SOURCE_DIR}/../tests/lua/threads"
+      COMMAND "../test.sh" "${CMAKE_CURRENT_BINARY_DIR}/leanlua")
+  endif()
+endif()

tests/lua/threads/util.lua

@@ -0,0 +1,11 @@
+-- Execute f, and make sure is throws an error
+function check_error(f)
+    ok, msg = pcall(function ()
+        f()
+        end)
+    if ok then
+       error("unexpected success...")
+    else
+       print("caught expected error: ", msg)
+    end
+end