Also, propagate around previous improvements to stream slurping.
Fix some test cases.

Change declare ignore to ignorable to make ACL happier.
Remove slot for if-component-dep-fails.
Update some tests and workaround a failure on ecl-bytecodes.

* fix sysdef-find-asdf (bug found by Attila Lendvai). Test case added.
* make compile-file* nicer wrt *compile-file-{failure|warnings}-behaviour*
 test case thanks to Stas Boukarev (lp#598018) + working around CLISP bug.
* allow for (setf (find-class asdf::foo) ...) to work more portably,
 to make cffi-grovel happy.