gnu: xpra: Update to 5.0.2

* gnu/packages/patches/xpra-4.2-install_libs.patch: Move to ...
* gnu/packages/patches/xpra-5.0-install_libs.patch: ... this file.
* gnu/packages/patches/xpra-4.2-systemd-run.patch: Move to ...
* gnu/packages/patches/xpra-5.0-systemd-run.patch: ... this file.
* gnu/local.mk (dist_patch_DATA): Update accordingly.
* gnu/packages/xorg.scm (xpra): Update to 5.0.2.
[source] <patches>:  Rename per version changes
[inputs]: Add cups.

Signed-off-by: Ludovic Courtès <ludo@gnu.org>

gnu/packages/patches/xpra-5.0-install_libs.patch

@@ -0,0 +1,42 @@
+Distribution specific patch, not going upstream
+
+This workaround for Gentoo interferes with our use of --no-compile during
+the 'install stage.
+
+diff --git a/setup.py b/setup.py
+index e254bf99c..90db55c3f 100755
+--- a/setup.py
++++ b/setup.py
+@@ -663,8 +663,6 @@ if modules_ENABLED:
+ # Utility methods for building with Cython
+ 
+ def add_cython_ext(*args, **kwargs):
+-    if "--no-compile" in sys.argv and not ("build" in sys.argv and "install" in sys.argv):
+-        return
+     if not cython_ENABLED:
+         raise ValueError(f"cannot build {args}: cython compilation is disabled")
+     if cython_tracing_ENABLED:
+@@ -1809,9 +1807,6 @@ else:
+             if root_prefix.endswith("/usr"):
+                 #ie: "/" or "/usr/src/rpmbuild/BUILDROOT/xpra-0.18.0-0.20160513r12573.fc23.x86_64/"
+                 root_prefix = root_prefix[:-4]
+-            for x in sys.argv:
+-                if x.startswith("--root="):
+-                    root_prefix = x[len("--root="):]
+             print(f"install_data_override.run() root_prefix={root_prefix}")
+             build_xpra_conf(root_prefix)
+ 
+@@ -1955,13 +1950,6 @@ else:
+             if uinput_ENABLED:
+                 add_data_files("lib/udev/rules.d/", ["fs/lib/udev/rules.d/71-xpra-virtual-pointer.rules"])
+ 
+-    #gentoo does weird things, calls --no-compile with build *and* install
+-    #then expects to find the cython modules!? ie:
+-    #> python2.7 setup.py build -b build-2.7 install --no-compile \
+-    # --root=/var/tmp/portage/x11-wm/xpra-0.7.0/temp/images/2.7
+-    #otherwise we use the flags to skip pkgconfig
+-    if ("--no-compile" in sys.argv or "--skip-build" in sys.argv) and not ("build" in sys.argv and "install" in sys.argv):
+-        pkgconfig = no_pkgconfig
+ 
+     if OSX and "py2app" in sys.argv:
+         import py2app    #@UnresolvedImport