MDEV-11864 main.view test uses CHECK PARTITION but does not check for the partition plugin

The test would pass even with skipped partitioning, because
CHECK PARTITION for a view works identically with enabled/disabled
partitioning; but if the server is compiled without partitioning
at all, it cannot execute the statement, and the test would fail.

Check for the presence of partitioning allows to skip the test
in this case, rather than let it fail

mysql-test/t/view.test

+--source include/have_partition.inc
 
 --disable_warnings
 drop table if exists t1,t2,t3,t4,t5,t6,t9,`t1a``b`,v1,v2,v3,v4,v5,v6;