bug#25492: floating point bug in 2.1.6

[Daniel Llorens]

See below.

The bug happens after commit 35a90592501ebde7e7ddbf2486ca9d315e317d09, ‘Add 
unboxed floating point comparison instructions.’


> ./meta/guile 
GNU Guile 2.1.6
Copyright (C) 1995-2016 Free Software Foundation, Inc.

Guile comes with ABSOLUTELY NO WARRANTY; for details type `,show w'.
This program is free software, and you are welcome to redistribute it
under certain conditions; type `,show c' for details.

Enter `,help' for help.
scheme@(guile-user)> (define x 0.0)
scheme@(guile-user)> (< x 1.0)
$1 = #t
scheme@(guile-user)> (< x 0.9)
$2 = #f