Modified bytecode JIT code to support llvm versions 8, 9, 10, 11, 12.
Additionally updated FindLLVM.cmake to the current version, found at
https://github.com/ldc-developers/ldc/blob/master/cmake/Modules/FindLLVM.cmake,
as well as making modifications suggested by Micah Snyder to check VERSION_LESS
in CMakeLists.txt to avoid having modifications to FindLLVM.cmake.
Previously we'd not clang-formatted the c++ bytecode files because:
A) It's a massive difference in format
B) I wasn't sure, at the time, which code was "ours"
Reformatting now that the LLVM source is all removed and before it gets
updated to support modern LLVM versions.
Bounds checks were too strict, causing the bytecode to abort when it shouldn't.
This happened when trying to access the last byte of an array, the verifier
was too conservative and considered to be out of bounds, when in fact it wasn't.
This is an update of the runtime verifier from the bytecode compiler.
