Comment # 1 on bug 1231346 from Jan Engelhardt

Cannot reproduce.

libpthread.so is not supposed to be in /usr/lib/virtualbox.
There is but one reason why VBoxSVC might search for a .so file in
/usr/lib/virtualbox: There was no "libpthread.so" in any system path that
matched the current architecture. But this is to be expected, too, because..

1. libpthread.so is a hint file and for software development scenarios only.
Its presence is *not guaranteed* on normal systems. *No program* should ever
attempt to dlopen "libpthread.so", but *must* use "libpthread.so.0".

2. glibc>=2.34 (or thereabouts) has abolished the libpthread.so hint file
altogether.

(The same goes for libdl.)