[flang] Remove needless "anyIntrinsicDefinedOps", fixing iterative expr analysis

The flag "anyIntrinsicDefinedOps" is always set nowadays, as there are intrinsic
modules that define operator(==) and (!=).  This disables the iterative
expression analysis mechanism, also unnecessarily, and it is possible to
overflow the stack when analyzing very deep expression trees like the ones
that show up in artificial stress tests.  Remove the flag.

Differential Revision: https://reviews.llvm.org/D159022