AliSQL: [Feature] Issue#8: SELECT FOR UPDATE WAIT

Summary:

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The feature provides a way to set lock wait timeout for some statement.

Usage:

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1.select ... for update [wait [n]|no_wait]

2.select ... lock in share mode [wait [n]|no_wait]

3.lock table ... [wait [n]|no_wait]

no_wait: the query not wait for locks, instead of return immeditly, and print

"ERROR 1205 (HY000): Lock wait timeout exceeded; try restarting transaction;"

wait [n]: n is wait time in second, after wait n seconds for locks,

return and print errors;