[lldb-mi] Correct regex in the symbol-list-lines test

Summary:
The test failed in case of compiling a test suite with
gcc (checked versions are 5.2.0 and 7.3.0) because it
adds one more line entry comparing to clang. It doesn't
break the test's logic, so I just added a regex that matches
this case.

Reviewers: tatyana-krasnukha, aprantl, clayborg

Reviewed By: aprantl

Subscribers: ki.stfu, lldb-commits

Differential Revision: https://reviews.llvm.org/D52101

llvm-svn: 342329