[test] Relax stderr expectations on targets with chatty output

Summary:
On some android targets, a binary can produce additional garbage (e.g. warning messages from the
dynamic linker) on the standard error, which confuses some tests. This relaxes the stderr
expectations for targets known for their chattyness.

Reviewers: tfiala, ovyalov

Subscribers: tberghammer, danalbert, srhines, lldb-commits

Differential Revision: http://reviews.llvm.org/D19114

llvm-svn: 266326