Upgrade to v19_20071207. This is the latest stable release.
The previous tarball portaudio-19.b1175 is dated Feb 11 2007.
Note: the ancient port audio/portaudio should be deprecated, but it is
still used by several ports; if you are still using it, please consider
a migration towards portaudio2.
Hint: if your port does not build with portaudio2, it may be outdated!