Fix function comments formatting and introduce reset_error() and set_error_if_unset()
Fix function comments formatting and introduce reset_error() and set_error_if_unset()

The set_error_if_unset() function can be used if you are not sure
whether the exception has been caught by catch_error() from libvirt
itself to set the error string if it's not set. The string is not
overwritten once it's already present.

Signed-off-by: Michal Novotny <8dce8af224790fd82cd80deb27431e4980a7ff31@redhat.com>

zippy2/libvirt-php,libvirt/libvirt-php,martijnotto/libvirt-php,KnightSwarm/libvirt-php,zippy2/libvirt-php,KnightSwarm/libvirt-php,martijnotto/libvirt-php,libvirt/libvirt-php,php/pecl-virtualization-libvirt,tucksaun/libvirt-php,libvirt/libvirt-php,php/pecl-virtualization-libvirt,php/pecl-virtualization-libvirt,KnightSwarm/libvirt-php,KnightSwarm/libvirt-php,vtolstov/libvirt-php,tucksaun/libvirt-php,vtolstov/libvirt-php,tucksaun/libvirt-php,KnightSwarm/libvirt-php,tucksaun/libvirt-php,php/pecl-virtualization-libvirt,vtolstov/libvirt-php,martijnotto/libvirt-php,zippy2/libvirt-php,vtolstov/libvirt-php,martijnotto/libvirt-php