tools: docs: parse_data_structs.py: add namespace support

tools: docs: parse_data_structs.py: add namespace support

C domain supports a ".. c:namespace::" tag that allows setting a
symbol namespace. This is used within the kernel to avoid warnings
about duplicated symbols. This is specially important for syscalls,
as each subsystem may have their own documentation for them.
This is specially true for ioctl.

When such tag is used, all C domain symbols have c++ style,
e.g. they'll become "{namespace}.{reference}".

Allow specifying C namespace at the exception files, avoiding
the need of override rules for every symbol.

Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
Message-ID: <cc27ec60ceb3bdac4197fb7266d2df8155edacda.1759329363.git.mchehab+huawei@kernel.org>