Move xenstore and libxc public headers to include subdir

Move xenstore and libxc public headers to include subdir

Also moves xc_dom.h to include as it is used often by other xen tools.
Use the new include subdirectories to build Xen tools, qemu-xen and
stubdoms.

Add the old libxc include path to the programs that need it to build,
on a case by case basis and commeting that they shouldn't require
internal libxc headers to build.

[ And: update QEMU_TRADITIONAL_REVISION to corresponding qemu patch
   - Ian jackson ]

Signed-off-by: Stefano Stabellini <stefano.stabellini@eu.citrix.com>