default _system_ca_path won't work on FreeBSD and change not taken into account

[p4tpr0]

The default value for _system_ca_path set in src/init is not right for FreeBSD. Changing this value with another path is not taken into account because code has hard-coded values:

$ sslmerge -i foobar.crt -o foobar-full.crt find: /etc/ssl/certs/: No such file or directory sed: 1: "$a-----END CERTIFICATE- ...": command a expects \ followed by text [!] bad certificate (maybe broken): foobar.crt

More importantly, upon error, the certificate file used as input is cleared (content erased).

[trimstray]

Great job!

I create environment on freebsd and I will try to generate this error.