16127 regex misidentifies mixed sets as singletons
Reviewed by: Igor Kozhukhov <igor@dilos.org>
Reviewed by: Yuri Pankov <yuri@aetern.org>

9007 import AT&T regex test suite
Reviewed by: Toomas Soome <tsoome@me.com>
Reviewed by: Robert Mustacchi <rm@joyent.com>
Approved by: Dan McDonald <danmcd@joyent.com>