[Libvir] PATCH: Remove use of PKG_CHECK_EXISTS

This patch removes the use of PKG_CHECK_EXISTS which is only available in new versions of pkg-config. Instead we use the 3rd and 4th args of the PKG_CHECK_MODULES macro to control the if-found/not-found behaviour. This allows us to auto-disable features if they're missing, rather than aborting the configure run. This patch also updates the SASL tests to support the value 'check' for auto-enable/disable like the rest of the modules. With this applied I can successfully run the following on RHEL-4 hosts with the default RPMs installed ./autogen.sh --without-xen make make dist Dan. -- |=- Red Hat, Engineering, Emerging Technologies, Boston. +1 978 392 2496 -=| |=- Perl modules: http://search.cpan.org/~danberr/ -=| |=- Projects: http://freshmeat.net/~danielpb/ -=| |=- GnuPG: 7D3B9505 F3C9 553F A1DA 4AC2 5648 23C1 B3DF F742 7D3B 9505 -=|