NH_HEAPLOG vs tile utilities

NH_HEAPLOG vs tile utilities

I just tried to build with MONITOR_HEAP defined in unixconf.h plus
WANT_WIN_X11=1 for make.  tile2x11 wouldn't link.  It doesn't use
alloc() and free(), but it does link with drawing.o, and drawing.o
has calls to free(), so MONITOR_HEAP makes it need nhfree() from
alloc.o.

All the miscellaneous tile utilities seem to link with drawing.o, so
they all need alloc.o too, and that drags in util/panic.o as well.
I've only changed it for Unix where I can actually test the change
but other platforms probably should do this too.  Or we need to redo
drawing.c so that the small subset of stuff utilities want is
separate from the code the core uses for that same stuff.