Use ManagedStatic and lazy initialization of cl::opt in libSupport to make it free...

Use ManagedStatic and lazy initialization of cl::opt in libSupport to make it free of global initializer

We can build it with -Werror=global-constructors now. This helps
in situation where libSupport is embedded as a shared library,
potential with dlopen/dlclose scenario, and when command-line
parsing or other facilities may not be involved. Avoiding the
implicit construction of these cl::opt can avoid double-registration
issues and other kind of behavior.

Reviewed By: lattner, jpienaar

Differential Revision: https://reviews.llvm.org/D105959