[lldb-mi] Fix hanging of target-select-so-path.test

Summary:
The target-select-so-path test might hang on
some platforms. The reason of that behavior
was in incorrect usage of Filecheck and lldb-mi
processes. Instead of redirecting lldb-mi's output
to Filecheck, we should run lldb-mi session,
finish the session, collect its output and then pass
it to Filecheck.
Also, this patch adds a timer to the test to prevent
it from hanging in the future.

Reviewers: tatyana-krasnukha, aprantl, teemperor

Reviewed By: tatyana-krasnukha, teemperor

Subscribers: apolyakov, aprantl, teemperor, ki.stfu, abidh, lldb-commits

Differential Revision: https://reviews.llvm.org/D52139

llvm-svn: 342915