switchspell can now work with a gtkspell that uses enchant by using
--enable-enchant option to ./configure. This was initially based on a patch
by Ignacio Vazquez-Abrams in Fedora, and reworked by me to support either
aspell or enchant:
https://bugzilla.redhat.com/show_bug.cgi?id=427949
Also fix a leaky error.