[lldb] Increase testsuite packet-timeout 5secs -> 1min

rL357954 did increase `packet-timeout` 1sec -> 5secs. Which is IMO about the
maximum timeout reasonable for regular use. But for testsuite I think the
timeout should be higher as the testsuite runs in parallel and it can be run
even on slow hosts and with other load (moreover if it runs on some slow arch).

I have chosen 60 secs, that should be enough hopefully.  Larger value could
make debugging with hanging `lldb-server` annoying.

This patch was based on this testsuite timeout:
http://lab.llvm.org:8014/builders/lldb-x86_64-fedora/builds/546/steps/test/logs/stdio
	FAIL: test_connect (TestGDBRemoteClient.TestGDBRemoteClient)
	   Test connecting to a remote gdb server
	----------------------------------------------------------------------
	Traceback (most recent call last):
	  File "/home/jkratoch/slave-lldb-x86_64-fedora/lldb-x86_64-fedora/llvm/tools/lldb/packages/Python/lldbsuite/test/functionalities/gdb_remote_client/TestGDBRemoteClient.py", line 13, in test_connect
	    process = self.connect(target)
	  File "/home/jkratoch/slave-lldb-x86_64-fedora/lldb-x86_64-fedora/llvm/tools/lldb/packages/Python/lldbsuite/test/functionalities/gdb_remote_client/gdbclientutils.py", line 480, in connect
	    self.assertTrue(error.Success(), error.description)
	AssertionError: False is not True : failed to get reply to handshake packet

Differential Revision: https://reviews.llvm.org/D65271

llvm-svn: 367234