Previously, setting `wsrep_sync_wait = 1` would have an effect on
both SELECT and SHOW statements.
This patch changes wsrep_sync_wait so that bitmask value 1 is used
for SELECT statements, while bitmask value 8 is reserved for SHOW
statements.
It is still possible to achieve sync wait on both SELECT and SHOW
statements by setting `wsrep_sync_wait = 9`.
Signed-off-by: Jan Lindström <jan.lindstrom@mariadb.com>