Add Forwarded: headers to the patches

Gbp-Dch: ignore

debian/patches/0001-Fix-cross-compilation-with-MPI.patch

@@ -2,6 +2,7 @@ From: =?utf-8?q?Timo_R=C3=B6hling?= <roehling@debian.org>
 Date: Tue, 14 Sep 2021 17:04:48 +0200
 Subject: Fix cross compilation with MPI
 
+Forwarded: https://gitlab.kitware.com/cmake/cmake/-/merge_requests/6537
 ---
  Modules/FindMPI.cmake | 36 +++++++++++++++++++++++++++++++++++-
  1 file changed, 35 insertions(+), 1 deletion(-)

debian/patches/0002-Prefer-Debian-default-version-of-Python.patch

@@ -2,6 +2,7 @@ From: =?utf-8?q?Timo_R=C3=B6hling?= <roehling@debian.org>
 Date: Mon, 13 Sep 2021 18:59:25 +0200
 Subject: Prefer Debian default version of Python
 
+Forwarded: not-needed
 ---
  Modules/FindPython/Support.cmake | 14 ++++++++++++++
  1 file changed, 14 insertions(+)