JSR-223 is always present so usage in <file:build.xml> is deprecated.
Fix compilation for SYS:RUN-PROGRAM on Java 6. Not expected to be
working very well. The general strategy is to undeprecate
SYS:RUN-SHELL-COMMAND is some manner that uses the Java 6 NIO plus
thread pools to drain IO.
Conditionalize on runtime platform of parts of our RUN-PROGRAM
Stub implementation of NIO async processor to drain queue.
TODO: figure out how why "cat /etc/passwd" doesn't ever give output?