meson: Check if -latomic is needed to link

Should fix #411 (closed)

src/meson.build

@@ -123,6 +123,7 @@ medialib = library('medialibrary', medialib_src,
         threads_dep,
         libxxhash_dep,
         macosx_dep,
+        atomic_dep,
     ],
     install: true,
     soversion: medialib_soversion,