Re: [libvirt] [PATCH v2 2/2] examples: Avoid gnulib, have standalone examples

Commit 0c6ad476 updated gnulib, which rearranged some of the conditions in gnulib wrapper headers such that compilation started failing on BSD systems when the normal system <unistd.h> tried to include another system header but instead got a gnulib wrapper header in an incomplete state; this is because gnulib headers only work if <config.h> is included first. Commit b6f78259 papered over the symptoms of that by including <config.h> in all the examples. But this logic is backwards - if our examples are truly meant to be stand-alone, they should NOT depend on how libvirt was configured, and should NOT depend on the gnulib fixes for system quirks. In particular, if an example does not need to link against libgnulib.la, then it also does not need to use -Ignulib in its compile flags, and likewise does not need to include <config.h> since none of the gnulib wrapper headers should be interfering. So, revert (most of) b6f78259 (except for the bogus pre-patch use of "config.h" in admin/logging.c: if config.h is included, it should be via <> rather than "", and must be before any system headers); then additionally nuke all mention of <config.h>, -Ignulib, and -lgnulib, making all of the examples truly standalone.