Fix memory leak introduced by _set_priv() crash fix. #3723

Always free the copied user and file-owner gid lists before copying a
new list from passwd_cache.
Use dlopen to open libganglia rather than linking with a specific version at build time. #3515

Some versions of libganglia cannot be used (e.g. 3.0.7, which is SL5 vintage).
In this case, fall back to using gmetric.
Merge branch 'V8_1_0-branch'