Make multiple KMASK lines for the same glyph work (qw)

It turns out that the later mask was overriding the earlier one.
Instead, combine the masks.  Resolve conflicts (no_monster_gen versus
!no_monster_gen for example) in favour of the later mask.

In particular, this allows grunt_temple_overflow_order_and_chaos_1
to place again; it was broken by 0.16-a0-179-g90b15e8.

Thanks to elliptic and gammafunk for helping find and debug the problem.

1 files changed, 1 insertions, 0 deletions

diff --git a/crawl-ref/source/mapdef.h b/crawl-ref/source/mapdef.h
index c48e59671b..d005cd5dff 100644
--- a/crawl-ref/source/mapdef.h
+++ b/crawl-ref/source/mapdef.h
@@ -842,6 +842,7 @@ struct map_flags
 
     map_flags();
     void clear();
+    map_flags &operator |= (const map_flags &o);
 
     static map_flags parse(const string flag_list[],
                            const string &s) throw(string);