Thread-unsafe initialization problems in Guile

[Mark H Weaver]

It would be good to fix these before 2.0.7 is released, but I'm a bit
uncertain of how best to do so, and I don't have time at the moment.

./posix.c:1375:            make_rw_port = scm_c_private_variable ("ice-9 popen",
./debug.c:217:    local_eval_var = scm_c_public_variable ("ice-9 local-eval", 
"local-eval");
./strports.c:541:      eval_string = scm_c_public_lookup ("ice-9 eval-string", 
"eval-string");

     Mark