Widelands fails to build with boost 1.77 due to a missing include in one
of Wideland's header files that was previously indirectly included by
boost 1.76.
* gnu/packages/patches/widelands-add-missing-map-include.patch: New file.
* gnu/local.mk (dist_patch_DATA): Add it.
* gnu/packages/games.scm (widelands)[source]: Add patch.
Signed-off-by: Leo Famulari <leo@famulari.name>