[Rpm-maint] fsync and package systems

[Colin Walters]

Hi,

See: https://bugs.freedesktop.org/show_bug.cgi?id=70366

TL;DR: Should triggers like ldconfig, gtk-update-icon-cache, and 
update-mime-database:

1) Not fsync, and honor an environment variable like 
PKGSYSTEM_ENABLE_FSYNC
2) Do fsync, and honor  PKGSYSTEM_DISABLE_FSYNC
3) Something else?