[Libvir] Finally - fix the build on Debian

The attached patch fixes three separate build problems on Debian: (1) The libtool autoconf macro is wrong in that it requires a C++ compiler and /lib/cpp, neither of which seems to be really needed. (2) If you pass -fstack-protector while compiling, then you also need to pass it while linking, so that gcc knows to link -lssp. (3) Long-standing problem that xencapstest.c won't compile --without-xen. Well, OK so I didn't actually fix (1), but I did add a note to the TODO file pointing out the problem. So you'll still need to install the Debian "g++" package before you can compile libvirt. Rich. -- Emerging Technologies, Red Hat - http://et.redhat.com/~rjones/ Registered Address: Red Hat UK Ltd, Amberley Place, 107-111 Peascod Street, Windsor, Berkshire, SL4 1TE, United Kingdom. Registered in England and Wales under Company Registration No. 03798903