Fix NPE error when creating table with bool column

[wubiaoi]

For #1857

[imay]

@wubiaoi

For old version storage, we don't support boolean type.
What will happen if you patch is applied when creating boolean type.

[wubiaoi]

@imay thanks for the comments.

For old version storage, we don't support boolean type.
What will happen if you patch is applied when creating boolean type.

Now, creating boolean type will thrown NPE instead of a syntax error.
ERROR 1064 (HY000): Unexpected exception: null

After applying this patch, the bool type will be supported similar to mysql.
eg.

create table booltest
(
id boolean null, 
value double sum null
)
engine=olap aggregate key(id) distributed by hash(id) buckets 6 properties("storage_type"="COLUMN","replication_num"="1");
insert into booltest values(false,1.3);
insert into booltest values(false,2.3);
insert into booltest values(true,0.3);
select * from booltest;

id	value
1	0.3
0	3.6

[imay]

LGTM