PR fortran/83344 Don't set bogus constant value

PR fortran/83344 Don't set bogus constant value

This patch does not fix PR 83344, but merely fixes an error where we
used to set a constant character length value from a non-constant
expression, and thus set it to some bogus value.

As a result of this, I have commented out part of the associate_22.f90
test which otherwise generates a warning message.

Regtested on x86_64-pc-linux-gnu.

gcc/fortran/ChangeLog:

2017-12-28  Janne Blomqvist  <jb@gcc.gnu.org>

	PR fortran/83344
	* resolve.c (resolve_assoc_var): Don't set the constant value
	unless the target is a constant expression.

gcc/testsuite/ChangeLog:

2017-12-28  Janne Blomqvist  <jb@gcc.gnu.org>

	PR fortran/83344
	* gfortran.dg/associate_22.f90: Comment out part of test.

git-svn-id: svn+ssh://gcc.gnu.org/svn/gcc/trunk@256021 138bc75d-0d04-0410-961f-82ee72b054a4