Disable PCRE process searching to avoid linking against libprce, which
would cause the build to fail due to a missing dependency. With the
--without-pcre switch, build fails due to an undefined reference, so do
it via CONFIGURE_VARS instead.

Signed-off-by: Rosen Penev <rosenp@gmail.com>
[disable PCRE process searching]
Signed-off-by: Stijn Tintel <stijn@linux-ipv6.be>