Merge branch 'fix-inefficiences-and-rename-nla_strlcpy'

Merge branch 'fix-inefficiences-and-rename-nla_strlcpy'

Francis Laniel says:

====================
Fix inefficiences and rename nla_strlcpy

This patch set answers to first three issues listed in:
https://github.com/KSPP/linux/issues/110

To sum up, the patch contributions are the following:
1. the first patch fixes an inefficiency where some bytes in dst were written
twice, one with 0 the other with src content.
2. The second one modifies nla_strlcpy to return the same value as strscpy,
i.e. number of bytes written or -E2BIG if src was truncated.
It also modifies code that calls nla_strlcpy and checks for its return value.
3. The third renames nla_strlcpy to nla_strscpy.

Unfortunately, I did not find how to create struct nlattr objects so I tested
my modifications on simple char* and with GDB using tc to get to
tcf_proto_check_kind.
====================

Link: https://lore.kernel.org/r/20201115170806.3578-1-laniel_francis@privacyrequired.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>