gdb: patch to use mach-o.h instead of bfd/mach-o.h

For unclear reasons, this doesn’t seem to work anymore. bfd/mach-o.h
is not accessible but mach-o.h is.

https://hydra.nixos.org/build/94542582

pkgs/development/tools/misc/gdb/default.nix

···
     sha256 = "0bnpzz0rl672xg5547q5qck2sxi6cnyixmk8bbb4gifw17ipwbw0";
   };
 
+  postPatch = if stdenv.isDarwin then ''
+    substituteInPlace gdb/darwin-nat.c \
+      --replace '#include "bfd/mach-o.h"' '#include "mach-o.h"'
+  '' else null;
+
   patches = [
     ./debug-info-from-env.patch
   ] ++ stdenv.lib.optionals stdenv.isDarwin [