[sssd PR#570][comment] p11_child: add OpenSSL support

[jhrozek]

URL: https://github.com/SSSD/sssd/pull/570
Title: #570: p11_child: add OpenSSL support

jhrozek commented:
"""
There seems to be one more glitch. If I don't have `softsm-util` installed, then configure says it can't be found, but then make fails with:
```
SOFTHSM2_CONF=./softhsm2_none.conf  --init-token  --label "SSSD Test Token" --pin 123456 --so-pin 123456 --free
bin/sh: --init-token: command not found
```
"""

See the full comment at https://github.com/SSSD/sssd/pull/570#issuecomment-392748811