Starting from 2.6.6, there are some build time options for spelling support.
./configure --enable-spell=type, Where type can be one of:
none: No spelling support.
static: Include a statically compiled sexy-spell-entry. *
libsexy: Link with -lsexy and use its spelling support. *
gtkspell: Link with -lgtkspell and use its spelling support. This option changes the input box to a GtkTextView, which you may not like! #
* = Uses enchant as its dictionary (this is a soft run-time dependancy only! That is, it uses dlopen and fails gracefully).
# = Uses aspell as its dictionary (this is a hard, link-time dependancy).
Hopefully the packager for your distribution will choose the most appropriate option. If in doubt, choose static, because it doesn't require anything special!