Fix minor shellcheck 0.7.2 warnings

The first warning of a misspelling is a false positive, so we annotate
the script accordingly.  As for the x-prefix warnings update the check
to use the conventional '[ -z <string> ]' syntax.

all-syslog.sh:46:47: warning: Possible misspelling: ZEVENT_ZIO_OBJECT
    may not be assigned, but ZEVENT_ZIO_OBJSET is. [SC2153]
make_gitrev.sh:53:6: note: Avoid x-prefix in comparisons as it no
    longer serves a purpose [SC2268]
man-dates.sh:10:7: note: Avoid x-prefix in comparisons as it no
    longer serves a purpose [SC2268]

Reviewed-by: Ahelenia Ziemiańska <[email protected]>
Reviewed-by: John Kennedy <[email protected]>
Signed-off-by: Brian Behlendorf <[email protected]>
Closes #12208 

0 files changed, 0 insertions, 0 deletions