[clang-tidy] add IgnoreMacros option to readability-uppercase-literal-suffix

And also enable it by default to be consistent with e.g.
modernize-use-using.

This helps e.g. when running this check on client code where the macro
is provided by the system, so there is no easy way to modify it.

Reviewed By: JonasToth, lebedev.ri

Differential Revision: https://reviews.llvm.org/D56025

llvm-svn: 350056