Crude Recast CMake workaround

Author: Capostrophic

extern/CMakeLists.txt

@@ -172,6 +172,8 @@ if(NOT OPENMW_USE_SYSTEM_RECASTNAVIGATION)
     set(RECASTNAVIGATION_DEMO OFF CACHE BOOL "")
     set(RECASTNAVIGATION_TESTS OFF CACHE BOOL "")
     set(RECASTNAVIGATION_EXAMPLES OFF CACHE BOOL "")
+    # FIXME: Remove when the used revision starts using >3.4 CMake
+    set(CMAKE_POLICY_VERSION_MINIMUM 3.10)
 
     include(FetchContent)
     FetchContent_Declare(recastnavigation