[CMake] If set we should pass LLVM_VERSION_INFO into config.h

Autoconf used to support setting LLVM_VERSION_INFO and there is some code filtered around llvm in Support/CommandLine.cpp and LTO/LTOCodeGenerator.cpp that uses it if it is set.

We also shouldn't be explicitly setting it as a define on llvm-shlib. It is pointless there because there is no code using it in llvm-shlib, and it is better to have it as part of the generated config.h so that it is available everywhere.

llvm-svn: 267490