[patch, fortran] Fix PR 92004, restore Lapack compilation

[Thomas Koenig]

Hello world,

this patch fixes an overzealous interpretation of F2018 15.5.2.4, where
an idiom of passing an array element to an array was rejected. This
also restores Lapack compilation without warning.

Regression-tested. OK for trunk?

Regards

	Thomas

2019-10-06  Thomas Koenig  <tkoenig@gcc.gnu.org>

	PR fortran/92004
	* gfortran.h (gfc_symbol): Add maybe_array.
	* interface.c (maybe_dummy_array_arg): New function.
	(compare_parameter): If the formal argument is generated from a
	call, check the conditions where an array element could be
	passed to an array.  Adjust error message for assumed-shape
	or pointer array.
	(gfc_get_formal_from_actual_arglist): Set maybe_array on the
	symbol if the actual argument is an array element fulfilling
	the conditions of 15.5.2.4.

2019-10-06  Thomas Koenig  <tkoenig@gcc.gnu.org>

	PR fortran/92004
	* gfortran.dg/argument_checking_24.f90: New test.
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