#46 crash due to freeing uninitialized variable

[Enrico Scholz]

See https://bugzilla.redhat.com/show_bug.cgi?id=819558 for details + patch from Rob Crittenden.

Error path is:

1. authHdrValue in setupCurlSession() is uninitialized
2. curl_easy_setopt() in setupAuth() succeeds (rc == CURLE_OK) --> authHdrValueP stays uninitialized
3. xmlrpc_strfree(authHdrValue) in setupCurlSession() is executed --> crash