setup: fix path of rust source dependencies

Appears that they were screwed up while moving the source files around.
Since rust-direct-ffi sources are automatically added to the depends list,
we only need to list hg-core sources.

setup.py

@@ -968,9 +968,8 extmodules = [
                   'hg-direct-ffi',
                   include_dirs=common_include_dirs,
                   depends=common_depends + ['mercurial/cext/charencode.h',
-                                            'mercurial/rust/src/lib.rs',
-                                            'mercurial/rust/src/ancestors.rs',
-                                            'mercurial/rust/src/cpython.rs']),
+                                            'rust/hg-core/src/ancestors.rs',
+                                            'rust/hg-core/src/lib.rs']),
     Extension('mercurial.cext.osutil', ['mercurial/cext/osutil.c'],
               include_dirs=common_include_dirs,
               extra_compile_args=osutil_cflags,