build: Add ${ACLOCAL_FLAGS} to ACLOCAL_AMFLAGS
build: Add ${ACLOCAL_FLAGS} to ACLOCAL_AMFLAGS

This is used by gnome-autogen.sh, and we need it when aclocal.m4 is
to be rebuilt by make, to avoid losing some aclocal paths.

GNOME/gnome-panel,GNOME/gnome-panel