CMakeLists: Fix build on Linux with CMake versions less than 3.25.

Source/Core/Core/CMakeLists.txt

@@ -755,7 +755,7 @@ elseif(UNIX)
 endif()
 
 # Bluez doesn't support all the communication modes on FreeBSD, so only using it on Linux
-if(CMAKE_SYSTEM_NAME MATCHES "Linux")
+if(LINUX)
   option(ENABLE_BLUEZ "Enables bluetooth support" ON)
   if(ENABLE_BLUEZ)
     find_package(BlueZ)