Log Message:
Fix guile support by repairing sed expression.

At configure time, guile --version is parsed to see if guile is new
enough, and our guile 1.8 is new enough.  But the sed expression,
documented to use BREs, wrongly uses \+ which is a modern RE
construct.  gsed interprets \+, and is hereby awarded a "test =="
badge of shame.  To fix this, change \+ to *.