Semantics refuses valid ELEMENTAL subprograms without dummy arguments,
but there's no such constraint in the standard; indeed, subclause
15.8.2 discusses the meaning of calls to ELEMENTAL functions with
arguments. Remove the check and its test.
Differential Revision: https://reviews.llvm.org/D111832
Adds missing semantic checks for ELEMENTAL functions and subroutines,
their dummy arguments, and their results from F'2018 15.8.1 C15100-15102.
Differential Revision: https://reviews.llvm.org/D109380