Fix: Avoid recursive variable expansion

* Quote CMAKE_SYSTEM_NAME to avoid recursive variable expansion

Author: singhgaurav1302

CMakeLists.txt

@@ -6,7 +6,7 @@ cmake_minimum_required(VERSION 3.16)
 project(googletest-distribution)
 set(GOOGLETEST_VERSION 1.16.0)
 
-if(NOT CYGWIN AND NOT MSYS AND NOT ${CMAKE_SYSTEM_NAME} STREQUAL QNX)
+if(NOT CYGWIN AND NOT MSYS AND NOT "${CMAKE_SYSTEM_NAME}" STREQUAL "QNX")
   set(CMAKE_CXX_EXTENSIONS OFF)
 endif()