ticket:11374 Regular Expression, improve checking of integer overflow.

git-svn-id: http://source.icu-project.org/repos/icu/icu/trunk/source@36792 251d0590-4201-4cf1-90de-194747b24ca1
ticket:11373 disable prematurely checked in test case.

git-svn-id: http://source.icu-project.org/repos/icu/icu/trunk/source@36793 251d0590-4201-4cf1-90de-194747b24ca1