- Added plugin_debug.test, multiple_index.test to innodb_fts suite
from mysql-5.7.

- commit c5b28e55 removes the warning
for InnoDB rebuilding table to add FTS_DOC_ID

- multiple_index test case  has MATCH(a) values are smaller
than in MySQL because ROLLBACK updates the stat_n_rows.

- st_mysql_ftparser_boolean_info structure conveys boolean
metadata to mysql search engine for every word in the query.
This structure misses the position value to store the correct
offset of every word. So phrase search queries in plugin_debug
test case with boolean mode for simple parser throws
wrong result.