add untracked test_stream_timeout into .gitignore and tests/Makefile.am

fix the error while make (after ./autogen.sh and ./configure):

~$ make
  CXX      test_stream.o
  CXXLD    test_stream
  CXX      test_stream_empty.o
  CXXLD    test_stream_empty
  CXX      test_stream_disconnect.o
  CXXLD    test_stream_disconnect
make[1]: *** No rule to make target `test_stream_timeout.c', needed by `test_stream_timeout.o'.  Stop.
make: *** [all-recursive] Error 1