fortran_vec: Fix instances of method chaining that may cause dangling pointer. * libinterp/corefcn/quandcc.cc (Fquadcc): Replace method chaining with a separate line for NDArray object to avoid going out of scope. * libinterp/corefcn/__ilu__.cc (F__iluc__): Obtain RowVector and ColumnVector objects in separate line to remain in scope. * libinterp/corefcn/__ichol__.cc (F__icholt__): Obtain RowVector object in separate line to remain in scope. For more details: https://octave.discourse.group/t/3132

--- a/libinterp/corefcn/quadcc.cc	Fri Aug 12 15:56:50 2022 +0200
+++ b/libinterp/corefcn/quadcc.cc	Mon Aug 15 00:22:55 2022 +0200
@@ -1668,7 +1668,8 @@
   else
     {
       // Intervals around singularities.
-      sing = args(4).array_value ().fortran_vec ();
+      NDArray arr = args(4).array_value ();
+      sing = arr.fortran_vec ();
       iivals[0] = a;
       std::copy_n (sing, nivals-1, iivals+1);
       iivals[nivals] = b;