Fix build with lld linker

Boost.Filesystem started to depend on Boost.Atomic on 1.77.0 version but lld
can't find library on its own:

libboost_atomic.so.1.79.0 => not found

CMakeLists.txt

@@ -432,6 +432,11 @@ endif()
 set(Boost_NO_BOOST_CMAKE ON)
 
 find_package(Boost 1.6.2 REQUIRED COMPONENTS ${BOOST_COMPONENTS} OPTIONAL_COMPONENTS ${BOOST_OPTIONAL_COMPONENTS})
+
+if(Boost_VERSION_STRING VERSION_GREATER_EQUAL 1.77.0)
+    find_package(Boost 1.77.0 REQUIRED COMPONENTS atomic)
+endif()
+
 if(OPENMW_USE_SYSTEM_MYGUI)
     find_package(MyGUI 3.4.1 REQUIRED)
 endif()

components/CMakeLists.txt

@@ -411,6 +411,10 @@ target_link_libraries(components
     yaml-cpp
     )
 
+if(Boost_VERSION_STRING VERSION_GREATER_EQUAL 1.77.0)
+    target_link_libraries(components ${Boost_ATOMIC_LIBRARY})
+endif()
+
 target_link_libraries(components ${BULLET_LIBRARIES})
 
 if (WIN32)