Fix: lookup libc name and pass it to dlopen()

The configure process now looks up the libc file name on a per OS basis
and this value is passed to dlopen() that handles the library lookup in
the system like stated in dlopen(3).

Fixes #12

Signed-off-by: David Goulet <dgoulet@ev0ke.net>
[HEAD MERGE] working version with fork(). no resize

Signed-off-by: David Goulet <dgoulet@ev0ke.net>
[MERGE] more fixes. Cleanup code

Signed-off-by: David Goulet <dgoulet@ev0ke.net>