Testing showed that it is always set and its value matches
always ts->kind (if available) or otherwise, if it is a variable,
the sym->ts.kind.
gcc/fortran/ChangeLog:
PR fortran/95837
* resolve.c (gfc_resolve_substring_charlen): Remove
bogus ts.kind setting for the expression.
gcc/testsuite/ChangeLog:
PR fortran/95837
* gfortran.dg/char4-subscript.f90: New test.