Merge minor library fixes from HEAD to 3.0.

Merge minor library fixes from HEAD to 3.0.

 - setenv() replacement
 - mimir's ASN1/SPNEGO typo fixes
 - (size_t)-1 fixes for push_* returns
 - function argument signed/unsigned correction
 - ASN1 error handling (ensure we don't use initiailsed data)
 - extra net ads join error checking
 - allow 'set security discriptor' to fail
 - escape ldap strings in libads.
 - getgrouplist() correctness fixes (include primary gid)

Andrew Bartlett