[PATCH v2] docs: scripts: sphinx-pre-install: Fix building docs with pyyaml package

[Thorsten Blum]

The Python module pyyaml is required to build the docs, but it is only
listed in Documentation/sphinx/requirements.txt and is therefore missing
when Sphinx is installed as a package and not via pip/pypi.

Add pyyaml as an optional package for Debian- and Red Hat-based distros to
fix building the docs if you prefer to install Sphinx as a package.

Signed-off-by: Thorsten Blum <thorsten.blum@xxxxxxxxxx>
---
Changes in v2:
- s/pyyaml/yaml/ as suggested by Vegard Nossum <vegard.nossum@xxxxxxxxxx>
- Make the check require the Python module; was optional
---
 scripts/sphinx-pre-install | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/scripts/sphinx-pre-install b/scripts/sphinx-pre-install
index 25aefbb35377..7e49a020c25e 100755
--- a/scripts/sphinx-pre-install
+++ b/scripts/sphinx-pre-install
@@ -361,6 +361,7 @@ sub give_debian_hints()
 {
 	my %map = (
 		"python-sphinx"		=> "python3-sphinx",
+		"yaml"			=> "python3-yaml",
 		"ensurepip"		=> "python3-venv",
 		"virtualenv"		=> "virtualenv",
 		"dot"			=> "graphviz",
@@ -395,6 +396,7 @@ sub give_redhat_hints()
 {
 	my %map = (
 		"python-sphinx"		=> "python3-sphinx",
+		"yaml"			=> "python3-pyyaml",
 		"virtualenv"		=> "python3-virtualenv",
 		"dot"			=> "graphviz",
 		"convert"		=> "ImageMagick",
@@ -951,6 +953,7 @@ sub check_needs()
 
 	# Check for needed programs/tools
 	check_perl_module("Pod::Usage", 0);
+	check_python_module("yaml", 0);
 	check_program("make", 0);
 	check_program("gcc", 0);
 	check_program("dot", 1);
-- 
2.39.2