+changes in sbcl-1.0.20 relative to 1.0.19:
+ * bug fix: fixed #427: unused local aliens no longer cause compiler
+ breakage. (reported by Stelian Ionescu, Andy Hefner and Stanislaw
+ Halik)
+ * bug fix: non-local exit from a WITH-ALIEN form no longer causes
+ alien-stack leakage. (reported by Andy Hefner)
+ * bug fix: PROGV signals an error when an attempt to violate declared
+ type of a variable or bind a constant is made.
+ * bug fix: SET signals an error when an attempt to violate declared
+ type of a variable is made.
+