devel/godot: unbreak on some non-x86 targets

In file included from platform/x11/godot_x11.cpp:30:
In file included from platform/x11/os_x11.h:33:
In file included from core/os/input.h:32:
In file included from core/object.h:32:
In file included from core/list.h:32:
In file included from core/os/memory.h:33:
core/safe_refcount.h:330:2: error: This platform cannot use safe refcount, compile with NO_THREADS or implement it.
#error This platform cannot use safe refcount, compile with NO_THREADS or implement it.

^

core/safe_refcount.h:338:3: error: unknown type name 'REFCOUNT_T'

REFCOUNT_T count;
^

PR: 214553
Reported by: pkg-fallout, linimon
Submitted by: Shane <FreeBSD@ShaneWare.Biz> (maintainer)