Use standard library getopt if available

Since CMake is checking for unistd.h and getopt it makes sense to
use getopt instead of sc_getopt if it is found. This adds some
ifdef logic in a couple of places and sc_getopt is not included
in the build if getopt is found.
Add check of ERRORusage_function in fedex.c

There was no check of ERRORusage_function before it was getting
called, so check-express was crashing if executed with no
arguments.