libv4l: fix libdvbv5 musl compile

Add optional copy of TEMP_FAILURE_RETRY macro.

Fixes [1]:

  ../../lib/libdvbv5/.libs/libdvbv5.so: undefined reference to `TEMP_FAILURE_RETRY'

[1] http://autobuild.buildroot.net/results/7aea0cbb9e7fe7d9919c9be04ba4567ddcf4e15e

Patch submitted upstream:
https://www.mail-archive.com/linux-media@vger.kernel.org/msg127134.html



[Peter: add upstream submission link as suggested by Baruch]
Signed-off-by: Peter Seiderer <ps.report@gmx.net>
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>