1. Un-deprecate SYS:RUN-SHELL-COMMAND. Use the pre Java 7 APIs as best
we can to support invoking programs, which essentially boils down to
being able to take a string, attempt to invoke it, and return its stdout
as a string.

2.    Re-code the SYS:RUN-PROGRAM Java callsite linkages so that ABCL
may be compiled on pre-Java7 JDKs. Produce an intelligible error if it
is invoked on a pre-Java7 JVM.

3.     Create an API to determine runtime JVM version. Wrap
UIOP/RUN-PROGRAM invocation in some sort of handler that will "fall
back" to using SYS:RUN-SHELL-COMMAND if it has compatible behavior via
specified args. This will potentially be fairly ugly code ASDF-side so
we might provide a shim that UIOP/RUN-PROGRAM invokes that contains the
logic outside the ASDF code base.

Any objections to this path forward?

--
"A screaming comes across the sky.  It has happened before, but there
is nothing to compare to it now."