Add configure.nat as a dependency of config.status

Add configure.nat as a dependency of config.status

After pulling Alan's change that added aarch64-sve-linux-ptrace.o to
configure.nat, I got an undefined reference to aarch64_sve_get_vq when
doing a "make clean && make".  It turns out that re-running configure
(./config.status --recheck) was needed to re-generate the Makefile with
aarch64-sve-linux-ptrace.o included in the object list.  Putting
configure.nat in the dependencies of config.status would make sure that
when we modify configure.nat, the configure script is re-ran.  I think
it also makes sense because configure.tgt and configure.host are also
there.

gdb/ChangeLog:

	* Makefile.in (config.status): Add configure.nat as a
	dependency.