PR 53796 Make inquire(file=, recl=) conform to F2018

In my original patch to fix PR 53796 I forgot to fix the behavior for
unconnected units when inquiring via filename. This patch fixes that.

Regtested on x86_64-pc-linux-gnu, committed as obvious.

libgfortran/ChangeLog:

2019-08-07  Janne Blomqvist  <jb@gcc.gnu.org>

	PR fortran/53796
	* io/inquire.c (inquire_via_filename): Set recl to -1 for
	unconnected units.

gcc/testsuite/ChangeLog:

2019-08-07  Janne Blomqvist  <jb@gcc.gnu.org>

	PR fortran/53796
	* gfortran.dg/inquire_recl_f2018.f90: Test for unconnected unit
	with inquire via filename.

From-SVN: r274160