The file j2se/make/sun/rmi/corbalogsources/Makefile uses CLASSPATH as a way to communicate the classpath to javac/java, and should use the -classpath option instead.

export CLASSPATH=$(JSCHEME_CLASSPATH)

This is a public environment variable and may be defined (or forced to be undefined) for other reasons.
This initially started with a build failure with the control makefiles: 'gnumake scsl' resulted in a:

    Exception in thread "main" java.lang.NoClassDefFoundError: jscheme/REPL