#20 Don't print error on compile failure

[Elliotte Rusty Harold]

Consider this:

ERR> NOTE - jester has tried to 'exec' "javac
-classpath
../jester/bin:lib/junit.jar:build/xom-1.1b5.jar:build/classes:lib/xalan.jar:lib/xercesImpl.jar
src/nu/xom/Attribute.java"
ERR> src/nu/xom/Attribute.java:773: duplicate case label
ERR> case '7':
ERR> ^

Jester jested and as a result the code failed to
compile. This is fine. No test here is needed. There's
no reason to generate any output for this case.