Floating point exception when reading plink formatted data

[CreRecombinase]

The variable segment_size_ver is never initialized when reading plink-formatted data. This leads to a divide by zero error on this line, causing the program to terminate. This can be replicated by running on the example plink-formatted data

[CreRecombinase]

The line in which the exception occurs assigns a variable that isn't used. The hard-coded -O3 compiler optimization flag is almost certainly why this didn't show up earlier.