If a compilation has multiple text sections, code in
textOff must compare the offset argument against the range
for each text section to determine which one it is in.
The comparison looks like this:
if uintptr(off) >= sectaddr && uintptr(off) <= sectaddr+sectlen
If the off value being compared is equal to sectaddr+sectlen then it
is not within the range of the text section but after it. The
comparison should be just '<'.