warnings: more Warray-bounds, Wdiscarded-qualifiers, Wzero-length-bounds

Bugzilla: https://bugzilla.redhat.com/2166789

Recent builds still have a few warnings that were not caught by the other MR for x86_64 and Aarch64, mostly:

• array-bounds from skbuff and vsock
• discarded-qualifiers from tty/serial
• zero-length-bounds in fs/udf
• format-truncation tools/thermal

Signed-off-by: Eric Chanudet echanude@redhat.com