Remove llvm version check from Makefile

[abadams]

It's redundant with the one in LLVM_Headers.h, so all it does is break every time we get a new LLVM version.

[alexreinking]

I would prefer to preserve the equivalent version check in CMake because I find it's better to know before you start building anything that you've picked up on the wrong copy of LLVM.

[abadams]

Sure. I figured that the Makefile being officially unsupported for third-parties meant that it's fine to remove some hand-holding from it.

[alexreinking]

Sure. I figured that the Makefile being officially unsupported for third-parties meant that it's fine to remove some hand-holding from it.

Of course! I was just documenting my rationale for not asking you to make the change across both build systems.

[abadams]

Failures unrelated