fdo#71936 Add Excel 2010 functions GAMMA.DIST, GAMMA.INV, GAMMALN.PRECISE

Change-Id: I96f6beb34c1ce7f7191c6e9d379145ba98320c87
Reviewed-on: https://gerrit.libreoffice.org/6775
Reviewed-by: Eike Rathke <erack@redhat.com>
Tested-by: Eike Rathke <erack@redhat.com>