watch: truncate command in non-8 bit mode

watch: truncate command in non-8 bit mode

When the screen width is not long enough to display the entire
command, watch puts three dots ... like elipses at the end of
the truncated line.

It's been like that for years, perhaps noone uses non 8-bit
watch?

References:
 commit 367b8bb616c6d52513b594ccb936d322a3f8b6c1

Signed-off-by: Craig Small <csmall@enc.com.au>