gnu: ganeti: Prepare for Sphinx 4.0.

* gnu/packages/patches/ganeti-sphinx-compat.patch: New file.
* gnu/local.mk (dist_patch_DATA): Adjust accordingly.
* gnu/packages/virtualization.scm (ganeti)[source](patches): Add it.

gnu/local.mk

@@ -1068,6 +1068,7 @@ dist_patch_DATA =						\
   %D%/packages/patches/ganeti-preserve-PYTHONPATH.patch		\
   %D%/packages/patches/ganeti-shepherd-master-failover.patch	\
   %D%/packages/patches/ganeti-shepherd-support.patch		\
+  %D%/packages/patches/ganeti-sphinx-compat.patch		\
   %D%/packages/patches/gash-utils-ls-test.patch			\
   %D%/packages/patches/gawk-shell.patch				\
   %D%/packages/patches/gcc-arm-bug-71399.patch			\

gnu/packages/patches/ganeti-sphinx-compat.patch

@@ -0,0 +1,24 @@
+Adjust documentation for Sphinx 4.0.
+
+Discussed upstream at <https://github.com/ganeti/ganeti/pull/1615>.
+
+diff --git a/doc/index.rst b/doc/index.rst
+--- a/doc/index.rst
++++ b/doc/index.rst
+@@ -119,7 +119,6 @@ Draft designs
+    design-hotplug.rst
+    design-internal-shutdown.rst
+    design-kvmd.rst
+-   design-location.rst
+    design-linuxha.rst
+    design-location.rst
+    design-lu-generated-jobs.rst
+diff --git a/lib/build/shell_example_lexer.py b/lib/build/shell_example_lexer.py
+--- a/lib/build/shell_example_lexer.py
++++ b/lib/build/shell_example_lexer.py
+@@ -79,4 +79,4 @@ class ShellExampleLexer(RegexLexer):
+ 
+ 
+ def setup(app):
+-  app.add_lexer("shell-example", ShellExampleLexer())
++  app.add_lexer("shell-example", ShellExampleLexer)

gnu/packages/virtualization.scm

@@ -519,6 +519,7 @@ firmware blobs.  You can
               (file-name (git-file-name name version))
               (patches (search-patches "ganeti-shepherd-support.patch"
                                        "ganeti-shepherd-master-failover.patch"
+                                       "ganeti-sphinx-compat.patch"
                                        "ganeti-haskell-compat.patch"
                                        "ganeti-haskell-pythondir.patch"
                                        "ganeti-disable-version-symlinks.patch"