octave: add patch for octave incorrectly failing on package builds

Patch comes from https://savannah.gnu.org/bugs/?func=detailitem&item_id=62436

pkgs/development/interpreters/octave/default.nix

@@ -119,6 +119,11 @@ let
       sha256 = "sha256-1KnYHz9ntKbgfLeoDcsQrV6RdvzDB2LHCoFYCmS4sLY=";
     };
 
+    patches = [
+      # https://savannah.gnu.org/bugs/?func=detailitem&item_id=62436
+      ./patches/bug62436.patch
+    ];
+
     buildInputs = [
       readline
       ncurses

pkgs/development/interpreters/octave/patches/bug62436.patch

@@ -0,0 +1,27 @@
+# HG changeset patch
+# User John Donoghue <john.donoghue@ieee.org>
+# Date 1652358904 14400
+#      Thu May 12 08:35:04 2022 -0400
+# Branch stable
+# Node ID 8c940cfcce257369677c09154da2aab2c56eaa79
+# Parent  63710f3bd9811c2d206ac9e7b4f47cf06c47e153
+* scripts/pkg/private/build.m: check configure and Makefile exist before trying to unlink them (Bug #62436)
+
+diff -r 63710f3bd981 -r 8c940cfcce25 scripts/pkg/private/build.m
+--- a/scripts/pkg/private/build.m	Wed May 11 09:44:55 2022 -0700
++++ b/scripts/pkg/private/build.m	Thu May 12 08:35:04 2022 -0400
+@@ -77,8 +77,12 @@
+     else
+       arch_abi = getarch ();
+       configure_make (desc, build_root, verbose);
+-      unlink (fullfile (build_root, "src", "configure"));
+-      unlink (fullfile (build_root, "src", "Makefile"));
++      if exist (fullfile (build_root, "src", "configure"), "file")
++        unlink (fullfile (build_root, "src", "configure"));
++      endif
++      if exist (fullfile (build_root, "src", "Makefile"), "file")
++        unlink (fullfile (build_root, "src", "Makefile"));
++      endif
+     endif
+     tar_name = [desc.name "-" desc.version "-" arch_abi ".tar"];
+     tar_path = fullfile (builddir, tar_name);