* configure.in: Document AC_SYS_LARGEFILE.
	* docs/hvsupport.html.in: Document HV support for virDomainBlockPeek.
	* include/libvirt/libvirt.h.in, src/driver.h, src/libvirt.c,
	src/libvirt_sym.version: Add virDomainBlockPeek infrastructure.
	* src/qemu_driver.c, src/test.c: Null versions of this call.
	* src/xen_unified.c, src/xend_internal.c, src/xend_internal.h,
	src/xm_internal.c, src/xm_internal.h: Xen implementation.
	* tests/sexpr2xmldata/sexpr2xml-curmem.xml,
	tests/sexpr2xmldata/sexpr2xml-no-source-cdrom.xml: XML output
	has been reordered slightly in the Xen driver, but should be
	functionally the same.