[flang] Check constant arguments to bit manipulation intrinsics even if not foldable

When some arguments that specify bit positions, shift counts, and field sizes are
constant at compilation time, but other arguments are not constant, the compiler
should still validate the constant ones.  In the current sources, validation is
only performed for intrinsic references that can be folded to constants.

Differential Revision: https://reviews.llvm.org/D140152