This patch adds a test program that generates a square wave of a given frequency,
length and sample rate. This is then resampled to another rate, rewound and the
rewound part is run through the resampler again. After that, the results of the
first and second resampler pass are compared.
Part-of: <https://gitlab.freedesktop.org/pulseaudio/pulseaudio/-/merge_requests/120>
