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

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>