This update for virtualbox fixes the following issues:

* VMM: reset the TSC on VM reset to work around a Windows bug (bug #16643)
* Audio: fixed memory leak when enabled with VRDP connections (5.1.24 regression; bug #16928)
* Audio: fixed creation of too many sound sinks on Linux hosts when using the PulseAudio backend (bug #16938)
* Audio: implemented record gain registers for AC'97 emulation; those are needed for newer Ubuntu guests which rely on those when controlling gain and muting the recording (capturing) levels
* Storage: fixed hang when using the emulated NVMe controller with the SPDK (bug #16945)
* Mouse: double click was not working with a precision touchpad (bug #14632)
* Linux hosts: properly bring up host-only network interfaces with iproute (5.1.24 regression; bug #16911)
* Linux hosts: provide Python 3 libraries for deb/rpm packages
* Windows guests: fixed automatic logons for Vista and newer Windows guests (5.1.24 regression; bug #16921)