Add "Failing Tests .." line to dosep logs

Summary:
-Buildbot parser depends on this line as start flag
-Will remove the dependency from buildbot parser, but it takes some time to take effect
-Will remove this line from printout after buildbot master reconfig

Reviewers: chaoren, vharron

Subscribers: lldb-commits

Differential Revision: http://reviews.llvm.org/D10110

llvm-svn: 238527