Fortran: accept both old and new-style relational operators in USE, ONLY

Fortran: accept both old and new-style relational operators in USE, ONLY

F2018:10.1.5.5.1(2) requires the same interpretation of old and new-style
relational operators.  As gfortran internally distinguishes between
these versions, we must match equivalent notations in
	USE module, ONLY: OPERATOR(op)
statements when reading modules.

gcc/fortran/ChangeLog:

	PR fortran/65454
	* module.c (read_module): Handle old and new-style relational
	operators when used in USE module, ONLY: OPERATOR(op).

gcc/testsuite/ChangeLog:

	PR fortran/65454
	* gfortran.dg/interface_operator_3.f90: New test.