Myself wrote:
Grep the output for "WARNING"; on SBCL, a warning will result in an ASDF compilation failure.
Just by skimming through it, I saw one type mismatch warning, one of those annoying DEFPACKAGE warnings, and an annoying CFFI DEFCTYPE warning.
Your options are to change the source, or toggle the variable that governs ASDF compilation failure behavior.
That said, the problem with *COMPILE-FILE-WARNING-BEHAVIOUR* is that it's applied *after* COMPILE-FILE finished; it would be much more intuitive if it failed right at the point a warning is signaled. More intuitive because the message of the warning would not be hidden somewhere in the backlog.
-T.