GNUmakefile missing from build dir in VPATH build

[James Youngman]

VPATH builds work for me in current coreutils head.  However,
"distcheck" gails.

GNUmakefile  exists in $(top_srcdir) but not the build directory.
Distcheck does "make distcheck-hook".  That's defined in the Makefile
(from $(top_srcdir)/Makefile.am):-

distcheck-hook: check-ls-dircolors
        $(MAKE) my-distcheck

Unfortunately my-distcheck is only defined in GNUmakefile, not in
Makefile.   So this error results:

[...]
mkdir coreutils-6.10.69-e0b96-dirty/_build
mkdir coreutils-6.10.69-e0b96-dirty/_inst
chmod a-w coreutils-6.10.69-e0b96-dirty
dc_install_base=`CDPATH="${ZSH_VERSION+.}:" && cd
coreutils-6.10.69-e0b96-dirty/_inst && pwd | sed -e
's,^[^:\\/]:[\\/],/,'` \
          && dc_destdir="${TMPDIR-/tmp}/am-dc-$$/" \
          && make  distcheck-hook \
          && cd coreutils-6.10.69-e0b96-dirty/_build \
          && ../configure --srcdir=.. --prefix="$dc_install_base" \
             \
          && make  \
          && make  dvi \
          && make  check \
          && make  install \
          && make  installcheck \
          && make  uninstall \
          && make  distuninstallcheck_dir="$dc_install_base" \
                distuninstallcheck \
          && chmod -R a-w "$dc_install_base" \
          && ({ \
               (cd ../.. && umask 077 && mkdir "$dc_destdir") \
               && make  DESTDIR="$dc_destdir" install \
               && make  DESTDIR="$dc_destdir" uninstall \
               && make  DESTDIR="$dc_destdir" \
                    distuninstallcheck_dir="$dc_destdir" distuninstallcheck; \
              } || { rm -rf "$dc_destdir"; exit 1; }) \
          && rm -rf "$dc_destdir" \
          && make  dist \
          && rm -rf coreutils-6.10.69-e0b96-dirty.tar.gz \
          && make  distcleancheck
make[1]: Entering directory `/home/james/source/GNU/coreutils/compile'
dc=$(sed -n '/static.*ls_codes\[/,/};'/p ../coreutils/src/dircolors.c
|sed -n '/^  *"/p'|tr , '\n'|sed 's/^  *//' |sed -n
's/^"\(..\)"/\1/p'|sort -u);                          \
        ls=$(sed -n '/static.*indicator_name\[/,/};'/\p
../coreutils/src/ls.c |sed -n '/^  *"/p'|tr , '\n'|sed 's/^  *//' |sed
-n 's/^"\(..\)"/\1/p'|sort -u);                          \
        test "$dc" = "$ls"
make my-distcheck
make[2]: Entering directory `/home/james/source/GNU/coreutils/compile'
make[2]: *** No rule to make target `my-distcheck'.
make[2]: Leaving directory `/home/james/source/GNU/coreutils/compile'
make[1]: *** [distcheck-hook] Error 2
make[1]: Leaving directory `/home/james/source/GNU/coreutils/compile'
make: *** [distcheck] Error 2