[CMake] Limit windows link options to MSVC (#60)

- enable building using ninja-clang on windows

Author: NikolaJelic

src/desktop/CMakeLists.txt

@@ -8,10 +8,11 @@ set_target_properties(${PROJECT_NAME} PROPERTIES OUTPUT_NAME NovaSwarm)
 
 if(WIN32)
   target_sources(${PROJECT_NAME} PRIVATE windows/app.rc)
-
-  set(subsystem $<IF:$<BOOL:$<CONFIG:Debug>>,CONSOLE,WINDOWS>)
-  target_link_options(${PROJECT_NAME} PRIVATE
-    /SUBSYSTEM:${subsystem}
-    /ENTRY:mainCRTStartup
-  )
+  if(MSVC)
+    set(subsystem $<IF:$<BOOL:$<CONFIG:Debug>>,CONSOLE,WINDOWS>)
+    target_link_options(${PROJECT_NAME} PRIVATE
+      /SUBSYSTEM:${subsystem}
+      /ENTRY:mainCRTStartup
+    )
+  endif()
 endif()