Add bash `-e` argument when running tests on Windows.
Add bash `-e` argument when running tests on Windows.

This makes the bash cmdline arguments consistent between running on Windows
and on other platforms using the `#!/bin/sh -e`.

librsync/librsync,sourcefrog/librsync,librsync/librsync,librsync/librsync,dbaarda/librsync,sourcefrog/librsync,librsync/librsync,dbaarda/librsync,dbaarda/librsync,sourcefrog/librsync,sourcefrog/librsync,dbaarda/librsync