exceptions/exceptions.hh: Use 'pragma once' as include guard
exceptions/exceptions.hh: Use 'pragma once' as include guard

Signed-off-by: Pekka Enberg <add4fcd06328a394f0ad91feda7ee057316dc5ed@cloudius-systems.com>

scylladb/scylla,rluta/scylla,dwdm/scylla,capturePointer/scylla,phonkee/scylla,asias/scylla,avikivity/scylla,stamhe/scylla,senseb/scylla,respu/scylla,justintung/scylla,victorbriz/scylla,acbellini/scylla,duarten/scylla,linearregression/scylla,shaunstanislaus/scylla,kjniemi/scylla,kjniemi/scylla,avikivity/scylla,victorbriz/scylla,senseb/scylla,justintung/scylla,glommer/scylla,victorbriz/scylla,kangkot/scylla,asias/scylla,duarten/scylla,eklitzke/scylla,bowlofstew/scylla,scylladb/scylla,capturePointer/scylla,gwicke/scylla,bowlofstew/scylla,kjniemi/scylla,kangkot/scylla,raphaelsc/scylla,asias/scylla,glommer/scylla,aruanruan/scylla,dwdm/scylla,senseb/scylla,bowlofstew/scylla,gwicke/scylla,raphaelsc/scylla,capturePointer/scylla,phonkee/scylla,stamhe/scylla,respu/scylla,justintung/scylla,raphaelsc/scylla,glommer/scylla,scylladb/scylla,gwicke/scylla,guiquanz/scylla,stamhe/scylla,rluta/scylla,acbellini/scylla,wildinto/scylla,rentongzhang/scylla,guiquanz/scylla,aruanruan/scylla,guiquanz/scylla,scylladb/scylla,linearregression/scylla,eklitzke/scylla,kangkot/scylla,aruanruan/scylla,phonkee/scylla,linearregression/scylla,rentongzhang/scylla,dwdm/scylla,wildinto/scylla,tempbottle/scylla,respu/scylla,shaunstanislaus/scylla,wildinto/scylla,tempbottle/scylla,rentongzhang/scylla,avikivity/scylla,eklitzke/scylla,duarten/scylla,acbellini/scylla,tempbottle/scylla,shaunstanislaus/scylla,rluta/scylla