Introduce Type::isIntegralOrEnumerationType(), to cover those places

Introduce Type::isIntegralOrEnumerationType(), to cover those places
in C++ that involve both integral and enumeration types. Convert all
of the callers to Type::isIntegralType() that are meant to work with
both integral and enumeration types over to
Type::isIntegralOrEnumerationType(), to prepare to eliminate
enumeration types as integral types.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@106071 91177308-0d34-0410-b5e6-96231b3b80d8