FLiT required binutils of a fairly recent version

[mikebentley15]

Bug Report

Describe the problem
Found today, the bisect functionality may not work unless you have a fairly recent version of binutils. Of note, version 2.25.1-32.base.el7_4.2 gave the error:

objcopy: BFD version 2.25.1-32.base.el7_4.1  assertion fail elf64-x86-64.c:341
objcopy: bisect-01/obj/solvers_gt_fPIC.o: invalid relocation type 42

But version 2.26.51.20151113 and version 2.31.1 did not give those errors.

Suggested Fix
Update the minimum required version of binutils in the documentation to 2.26

Alternative approaches:
Find another way to do what we are using objcopy to perform. Notably, we could write our own ELF parser. We only need the functionality to weaken symbols, perhaps rename symbols, and we could get more functionality out of bisect if we made something that could strengthen weak symbols into strong symbols.

If this approach is appealing, make a new issue requesting an ELF parser. You can reference this issue and/or reference that new issue from this one to link them together.