[DrJava] update build-common.xml

[James I-C. H. <jh...@ow...>]

I've committed a version of build-common.xml that fixes the bug where
compiling from the drjava directory would also compile dynamicjava files.
I disabled Ant's javac default searching mechanism that attempts to find
all referenced source files and compile them.

Also, the 1.4.1 SDK/JSR14 2.2 version of do-compile is the default version
again.  This is for the benefit of the developers in comp312, who are
using this configuration.

James