Add missing dict-clear! export
Fix util.match bug
Temporary fix for SEGV with (cond (1 2 . 3))

https://github.com/shirok/Gauche/issues/47

The root cause of this is util.match bug.  The fix is in commit 867419d44.
However, compile.scm is compliled with 0.9.4 util.match so the bug won't
go away until after releasing 0.9.5.  This fix is a transient solution;
should be removed after 0.9.5 release.