gnu: pulseaudio: Fix CVE-2014-3970 and intermittent test failures.

* gnu/packages/patches/pulseaudio-CVE-2014-397.patch: New file.
* gnu/packages/patches/pulseaudio-fix-mult-test.patch: New file.
* gnu-system.am (dist_patch_DATA): Add them.
* gnu/packages/pulseaudio.scm (pulseaudio): Add patches.