Fix for bug #11765505 - "58480: LARGE_TESTS.LOCK_TABLES_BIG

IS FAILING".

The problem was that large_tests.lock_tables_big test was
failing due to exceeding open files limit on platforms where
this limit was set too low (this test simultaneously opens
approx. 6000 files).

This patch solves this issue by ensuring that this test is
skipped on such platforms.

mysql-test/suite/large_tests/t/lock_tables_big.test

 #
 # Bug#24509 cannot use more than 2048 file descriptors on windows
 #
+
+#
+# This test requires approximately 6000 of files to be open simultaneously.
+# Let us skip it on platforms where open files limit is too low.
+let $max_open_files_limit= `SELECT @@open_files_limit < 6100`;
+if ($max_open_files_limit)
+{
+  skip Need open_files_limit to be greater than 6100;
+}
+
 --disable_query_log
 create database many_tables;
 use many_tables;
@@ -19,14 +29,14 @@ while ($i)
 }
 
 #lock all tables we just created (resembles mysqldump startup is doing with --all-databases operation)
-#There will be 3 descriptors for each table (table.FRM, table.MYI and table.MYD files) means 9000 files
+#There will be 2 descriptors for each table (table.MYI and table.MYD files) means 6000 files
 #descriptors altogether. For Microsoft C runtime, this is way too many.
 
 eval LOCK TABLES $table_list;
 unlock tables;
 
 drop database many_tables;
---disable_query_log
+--enable_query_log
 --echo all done