analyzer: add test coverage for gfortran ICE fix [PR 93779]

PR analyzer/93779 reports an ICE in gfortran with -fanalyzer
that was fixed for GCC 10 by a workaround in
f76a88eb; the tree code in
question is a FUNCTION_DECL.

Given that I want to rework the above patch at some point, it seems
prudent to add test coverage to ensure the ICE doesn't come back,
which this patch does.

gcc/testsuite/ChangeLog:
	PR analyzer/93779
	* gfortran.dg/analyzer/pr88304-2.f90: New test, adapted from
	gfortran.fortran-torture/compile/pr88304-2.f90

gcc/testsuite/ChangeLog

+2020-02-18  David Malcolm  <dmalcolm@redhat.com>
+
+	PR analyzer/93779
+	* gfortran.dg/analyzer/pr88304-2.f90: New test, adapted from
+	gfortran.fortran-torture/compile/pr88304-2.f90
+
 2020-02-18  Mark Eggleston  <mark.eggleston@codethink.com>
 
 	PR fortran/93603

gcc/testsuite/gfortran.dg/analyzer/pr88304-2.f90

+! Copy of gfortran.fortran-torture/compile/pr88304-2.f90
+! as a regression test for ICE with -fanalyzer (PR analyzer/93779)
+
+module pr88304
+  implicit none
+  integer :: p
+contains
+  function foo (x, y, z, w)
+    integer, intent(in) :: x, y
+    character(*), optional, intent(out) :: z
+    integer, optional, intent(out) :: w
+    integer :: foo
+    foo = 1
+  end function foo
+  subroutine bar ()
+    integer :: s
+    s = baz (1)
+  contains
+    function baz (u)
+      integer, intent(in) :: u
+      integer :: baz
+      integer :: q
+      integer :: r (10)
+      r = 0
+      baz = 1
+      q = foo (p, r(u), w = baz)
+    end function baz
+  end subroutine bar
+end module pr88304