Use configure --libexecdir=BASEDIR to set LIBEXEC

The current usage of LIBEXEC is bogus. It describes the directory for
private xen executables. Other places create their own, similar
libexecdir path as $prefix/lib/xen/*.

Additional two other variables are used to describe similar paths:
PRIVATE_BINDIR and PRIVATE_PREFIX

The autotools configuration refers to libexec as a directory for
executables and stuff which is called by other programs, not by the
user.

Adjust all places that want libexecdir as a target path. LIBEXEC refers
now to the base directory. Three convenience variables are used to refer
to paths to private binaries, libs and include files.

Most users of LIBEXEC are updated to use LIBEXEC_BIN because that is
what they want.

Users of PRIVATE_BINDIR are updated to use LIBEXEC_BIN because that is
what they want.

An internal libxl function was removed. A single helper to retrieve
LIBEXEC_BIN remains.

As suggested by the docs, configure appends the package name to LIBEXEC
to make sure the provided directory really refers to xen. This makes
sure "make uninstall" preserves the real libexecdir.

Signed-off-by: Olaf Hering <olaf@aepfle.de>
Use configure --prefix=DIR to set PREFIX

PREFIX is set by configure --prefix=DIR, nothing outside
tools,docs,stubdom is using this variable.

Signed-off-by: Olaf Hering <olaf@aepfle.de>
Add configure --enable-rpath

This fixes the tools when xen is configured with --prefix=/odd/path

Signed-off-by: Olaf Hering <olaf@aepfle.de>
tools: remove private copies of includedir and libdir from libxenstat

They are wrong and unused.

Signed-off-by: Olaf Hering <olaf@aepfle.de>
tools: use Paths.mk also for tools build

Signed-off-by: Olaf Hering <olaf@aepfle.de>
Remove unused exec_prefix from Paths.mk

Signed-off-by: Olaf Hering <olaf@aepfle.de>
rerun autogen.sh

Signed-off-by: Olaf Hering <olaf@aepfle.de>