tools/docs,scripts: sphinx-*: prevent sphinx-build crashes

On a properly set system, LANG and LC_ALL is always defined.
However, some distros like Debian, Gentoo and their variants
start with those undefioned.

When Sphinx tries to set a locale with:

	locale.setlocale(locale.LC_ALL, '')

It raises an exception, making Sphinx fail. This is more likely
to happen with test containers.

Add a logic to detect and workaround such issue by setting
locale to C.

Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>
Message-ID: <1d0afad8fe3d83182be3a08eb00dd71322e23e69.1758196090.git.mchehab+huawei@kernel.org>
Signed-off-by: Jonathan Corbet <corbet@lwn.net>

tools/docs/sphinx-pre-install

@@ -26,6 +26,7 @@ system pacage install is recommended.
 """
 
 import argparse
+import locale
 import os
 import re
 import subprocess
@@ -422,8 +423,19 @@ class MissingCheckers(AncillaryMethods):
         """
         Gets sphinx-build version.
         """
+        env = os.environ.copy()
+
+        # The sphinx-build tool has a bug: internally, it tries to set
+        # locale with locale.setlocale(locale.LC_ALL, ''). This causes a
+        # crash if language is not set. Detect and fix it.
         try:
-            result = self.run([cmd, "--version"],
+            locale.setlocale(locale.LC_ALL, '')
+        except Exception:
+            env["LC_ALL"] = "C"
+            env["LANG"] = "C"
+
+        try:
+            result = self.run([cmd, "--version"], env=env,
                               stdout=subprocess.PIPE,
                               stderr=subprocess.STDOUT,
                               text=True, check=True)