Also add fFractionOfSecond and nFractionDecimals to obtain the
remaining fraction of second.
In preparation to use this in the number formatter and other
places that obtain the wall clock time particles, which likely so
far use bad rounding as well.
Change-Id: I4fbea4165c560646438b06c340756c97dafa7c78
Reviewed-on: https://gerrit.libreoffice.org/59700
Reviewed-by: Eike Rathke <erack@redhat.com>
Tested-by: Jenkins