Concolic testing of compiler output

[xermicus]

This is an idea I had a while ago. Don't have time for now so this issue serves just as a reminder:

We could try to make use of concolic testing, particularly for comparing our compiler output against what solc produces. E.g. whether a function compiled by either one compiler produces the exact same output, given identical input. Due to the difference of the EVM vs. our supported targets (or possibly we could test against LLVM IR as well), the comparison would be on a abstract level.