[SSSD] [PATCHES] Bugs in path_utils path_concat()

[Stephen Gallagher]

Patch 0001: Handle off-by-one error in path_concat()
Fixes https://fedorahosted.org/sssd/ticket/1230

Patch 0002: While fixing the above error, I noticed that path_concat()
would also get it wrong if we passed "/" for head.