[Bug fortran/90744] [7/8/9/10 Regression] Bogus length for character temporaries passed to external procedures since r268992

[trnka at scm dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=90744

--- Comment #2 from Tomáš Trnka <trnka at scm dot com> ---
Looks like the issue appears if a particular external procedure is called for
the second time. Replacing the seemingly useless "if" with just two calls leads
to one correct and one miscompiled call:

   subroutine DoTest()
      call convrs('A',getstr())
      call convrs('B',getstr())
   end subroutine


dotest ()
{
  {
    static integer(kind=8) slen.0;
    character(kind=1)[1:slen.0] * pstr.1;

        typedef character(kind=1) struct character(kind=1)[1:slen.0][1:slen.0];
    pstr.1 = 0B;
    slen.0 = 0;
    getstr (&pstr.1, &slen.0);
    convrs (&"A"[1]{lb: 1 sz: 1}, pstr.1, 1, slen.0);
    __builtin_free ((void *) pstr.1);
  }
  {
    static integer(kind=8) slen.2;
    character(kind=1)[1:slen.2] * pstr.3;

        typedef character(kind=1) struct character(kind=1)[1:slen.2][1:slen.2];
    pstr.3 = 0B;
    slen.2 = 0;
    getstr (&pstr.3, &slen.2);
    convrs (&"B"[1]{lb: 1 sz: 1}, pstr.3, 1, &slen.2);
    __builtin_free ((void *) pstr.3);
  }
}