(Bug #36285, rb://9).

innodb-index.test, innodb-index.result: Set innodb_lock_wait_timeout as
a session variable instead of relying on the global value.

innodb-index-master.opt: Remove.

innodb-timeout.test: Test that setting the innodb_lock_wait_timeout
works as advertised.

thd_lock_wait_timeout(): New function, to retrieve the lock wait timeout
for a given MySQL client connection (thd), or the global value (thd==NULL).

srv_lock_wait_timeout, innobase_lock_wait_timeout: Remove.

Replace MYSQL_SYSVAR_LONG(lock_wait_timeout)
with MYSQL_THDVAR_ULONG(lock_wait_timeout).