Uninterpreted functions with result types containing Bit don't work

[brianhuffman]

For example:

sawscript> foo <- define "foo" {{ (True, False) }}
sawscript> prove (unint_z3 ["foo"]) {{ foo == foo }}

"prove" (<stdin>:1:1):
"unint_z3" (<stdin>:1:8):
could not create uninterpreted type for Prelude.Bool