Work around clock_gettime kernel bug on Linux x32

On Linux x32, the clock_gettime VDSO currently falls back to the x86-64
syscall, so allow that as well as its x32 sibling.

Bug-Debian: https://bugs.debian.org/849923
Forwarded: no
Last-Update: 2017-01-03

Patch-Name: sandbox-x32-workaround.patch