- When creating an index for the sort, the number of rows plus 1 is used 
to allocate a buffer.  In this test case, the number of rows 4294967295 
is the max value of an unsigned integer, so when 1 was added to it, a 
buffer of size 0 was allocated causing the crash.
- Create new test suite for this bug's test suite as per QA.


myisam/sort.c:
  Bug#27029 alter table ... enable keys crashes mysqld on large table
  - Check to make sure the value of records is < UINT_MAX32 to avoid a 
  false positive on the remaining condition.
mysql-test/suite/large_tests/README.TXT:
  Bug#27029 alter table ... enable keys crashes mysqld on large table
  - New testsuite for large tests.
  - Added mtr hint for potential testers.
mysql-test/suite/large_tests/r/alter_table.result:
  Bug#27029 alter table ... enable keys crashes mysqld on large table
  - New testsuite for large tests.
  - Added results for bug.
mysql-test/suite/large_tests/t/alter_table.test:
  Bug#27029 alter table ... enable keys crashes mysqld on large table
  - New testsuite for large tests.
  - Added test for bug.