games/xconq: Fix build with Clang 6

./../bitmaps/lookglass.b:6:4: error: constant expression evaluates to 248 which cannot be narrowed to type 'char' [-Wc++11-narrowing]

0xf8, 0x00, 0x04, 0x01, 0x02, 0x02, 0x01, 0x04, 0x01, 0x04, 0x01, 0x04,
^~~~

http://beefy12.nyi.freebsd.org/data/head-amd64-default/p475478_s336801/logs/errors/xconq-7.5.0.0.p.0.20050612_1.log