New-ish files 'engrave', 'epitaph', and 'bogusmon' added for 3.6.0
were not handled by playground setup. NetHack runs without them so
limited testing didn't notice.
Add 'makedefs -s' to build them and include them in installed files.
Also, remove 'makedefs -m' and obsolete monstr.c.
6ecf97f6e3