If you use --prefix and then "-x LD_LIBRARY_PATH", the rsh pls would
take great pains to ensure that PATH and LD_LIBRARY_PATH were setup
correctly on the local and remote nodes, but then the fork pls would
blitely overwrite LD_LIBRARY_PATH with what the user exported (i.e.,
most likely without our prefix). This patch takes care of that -- the
fork pls examines the incoming environment, and if it sees PATH or
LD_LIBRARY_PATH, it re-prefixes those variables.
This commit was SVN r7566.
d172088dd3