action: make a note that we may not null-terminate private strings

action: make a note that we may not null-terminate private strings

Coverity complains that a 7-byte string may not be null-terminated when copied
into act->data (size 7). This is fine, make a note of it.

All the strings in xkeyboard-config only use 6 bytes + null terminator so this
won't be an issue. The server (the only user of these) uses an 8-byte array
and forcibly null-terminates the string, see XkbDDXPrivate().

Everything else treats it as byte-array size 7 anyway so whether it's
null-terminated doesn't matter.

Signed-off-by: Peter Hutterer <peter.hutterer@who-t.net>