gdbserver: fix the standalone build

gdbserver: fix the standalone build

When directly invoking gdb/gdbserver/configure && make, the build will
fail because the $(host_alias) is empty and thus create-version.sh does
not get enough parameters.

The output of gdbserver --version without this patch (built like above):

  [...]
  This gdbserver was configured as ""

After applying this patch:

  [...]
  This gdbserver was configured as "x86_64-unknown-linux-gnu"

2013-06-28  Mircea Gherzan  <mircea.gherzan@intel.com>

gdbserver:

	* configure.ac (version_host, version_target): Set and AC_SUBST
	them.
	* configure: Rebuild.
	* Makefile.in (version_host, version_target): Get from
	configure.
	(version.c): Use $(version_host) and $(version_target).

Change-Id: Id48240532ad3d624ec78867a6db5ebd4c09583ff
Signed-off-by: Mircea Gherzan <mircea.gherzan@intel.com>