When using out-of-tree builds, the certificate files must be located. Support the use of a 'srcdir' environment variable for this.
When using out-of-tree builds, the certificate files must be located.
Support the use of a 'srcdir' environment variable for this.

Patch by: Alon Bar-Lev <alon.barlev{_AT_}gmail.com>

jandre/serf,jandre/serf,jandre/serf,jandre/serf