Disabled gcol.innodb_virtual_fk

Constant failures with:
"InnoDB: tried to purge non-delete-marked record in index"

mysql-test/suite/gcol/disabled.def

+##############################################################################
+#
+#  List the test cases that are to be disabled temporarily.
+#
+#  Separate the test case name and the comment with ':'.
+#
+#    <testcasename> : BUG#<xxxx> <date disabled> <disabler> <comment>
+#
+#  Do not use any TAB characters for whitespace.
+#
+##############################################################################
+gcol.innodb_virtual_fk: Constant failures "InnoDB: tried to purge non-delete-marked record in index"