endian.h: avoid some Wconversion warnings
endian.h: avoid some Wconversion warnings

Change-Id: Ic77bd0dd6ac2355eaf3e11811fba7604c782d9d6
Reviewed-on: https://gerrit.libreoffice.org/17307
Reviewed-by: Eike Rathke <ca97d066ec547ed7b5f176c01ed86da55dede03e@redhat.com>
Tested-by: Eike Rathke <ca97d066ec547ed7b5f176c01ed86da55dede03e@redhat.com>

JurassicWordExcel/core,JurassicWordExcel/core,JurassicWordExcel/core,JurassicWordExcel/core,JurassicWordExcel/core,JurassicWordExcel/core,JurassicWordExcel/core,JurassicWordExcel/core,JurassicWordExcel/core,JurassicWordExcel/core