Use ipv4 localhost address in lldb-server tests

Since the ipv6 patch, we've experienced occasional flakyness in
lldb-server tests. This was due to the fact that lldb-server was trying
to listen on both v4 and v6 localhost sockets (and consider it a success
if at least one of them succeeded), while the test framework was only
trying to connect to the v4 one.

This change makes sure lldb-server only listens on the v4 socket.

llvm-svn: 316391

lldb/packages/Python/lldbsuite/test/tools/lldb-server/gdbremote_testcase.py

@@ -369,7 +369,7 @@ class GdbRemoteTestCaseBase(TestBase):
                 ["*:{}".format(self.port)]
         else:
             commandline_args = self.debug_monitor_extra_args + \
-                ["localhost:{}".format(self.port)]
+                ["127.0.0.1:{}".format(self.port)]
 
         if attach_pid:
             commandline_args += ["--attach=%d" % attach_pid]