[Libvir] Request for changing #include directives to conform to Linux standard

The 'virterror.h' file has an #include directive to "libvirt.h" which isn't correct because libvirt include files are installed on a sub-directory named 'libvirt'. i.e. when libvirt is compiled with configure --script=/usr, then libvirt files are installed in /usr/include/libvirt/.* To be standard with Linux usage of include files, the correct directive in virterror.h will be: #include <libvirt/libvirt.h> instead of: #include "libvirt.h" and in C/C++ source files using libvirt, there is just to include libvirt with: #include <libvirt/libvirt.h> #include <libvirt/virterror.h> This is conform to Linux usage of include files and this permit to simplify Makefile(s) because there is no need to add option -I/usr/include/libvirt to compile sources files. Regards.