Analysis: There were two problems. (1) if partition table was
created using lower_case_tables = 1 on windows we did find the
correct table but we did not set share->ib_table correctly.
(2) we did open table on dictionary but did not increase
mysql_open_tables.

Fix: In xtradb allow access to tables with incorrect
lower case names (warning is printed to error log). If
table is opened increase mysql_open_tables count to avoid
crash on flush tables.