Added a test case from a PR that was fixed by something else.

2020-04-12  Thomas Koenig  <tkoenig@gcc.gnu.org>

	PR fortran/94091
	* gfortran.dg/char_length_22.f90: New test.

Committed ChangeLog entry.

gcc/testsuite/ChangeLog

+2020-04-12  Thomas Koenig  <tkoenig@gcc.gnu.org>
+
+	PR fortran/94091
+	* gfortran.dg/char_length_22.f90: New test.
+
 2020-04-12  Iain Sandoe  <iain@sandoe.co.uk>
 
 	* gcc.target/i386/indirect-thunk-1.c: Adjust for fno-common

gcc/testsuite/gfortran.dg/char_length_22.f90

+! { dg-do compile }
+! { dg-options "-O -Wall" }
+! PR 94091 - this used to give a bogus warning.
+! Test case by "MikeS".
+program tester
+  character(50) cname,fred
+  fred='1234567890123456789012345678901234567890' ! 40 characters
+  kk=len_trim(fred)
+  cname=fred(5:kk)
+  print *,kk,cname
+end program tester