[libvirt] clang vs. libvirt

I've been running the clang static analyzer against libvirt regularly, but it's usually been that of F12 or F13. Yesterday I used rawhide's version of clang: scan-build -o clang ./autogen.sh --enable-compile-warnings=error && scan-build -o clang make -j6 and it spotted a few new problems. Most are false positives, but a few were not. Here are the latest additions. I have an additional handful of patches that address the remaining false positives, and will post those later today.