fix generation of random q-ary matrices
fix generation of random q-ary matrices

dstehle/fplll,fplll/fplll,dstehle/fplll,cr-marcstevens/fplll,dstehle/fplll,cr-marcstevens/fplll,fplll/fplll,shi-bai/fplll,shi-bai/fplll,blowfish880/fplll,fplll/fplll,cr-marcstevens/fplll,shi-bai/fplll,fplll/fplll,fplll/fplll,blowfish880/fplll,shi-bai/fplll,cr-marcstevens/fplll,blowfish880/fplll