repair it

Multi-table delete that is optimized with QUICK_RANGE reports table
corruption.

DELETE statement must not use KEYREAD optimization, and sets
table->no_keyread to 1. This was ignored in QUICK_RANGE optimization.

With this fix QUICK_RANGE optimization honors table->no_keyread
value and does not enable KEYREAD when it is requested.


mysql-test/r/index_merge.result:
  Fixed a test case according to fix for bug#25048.
mysql-test/r/index_merge_ror.result:
  A test case for bug#25048.
mysql-test/t/index_merge_ror.test:
  A test case for bug#25048.
sql/opt_range.cc:
  Do not use key read when head->no_keyread is set.