POSIX sed only has -e, -f, and -n options.
doc/pspp.xml: doc/pspp.texinfo $(doc_pspp_TEXINFOS)
@$(MKDIR_P) doc
- $(MAKEINFO) $(AM_MAKEINFOFLAGS) --docbook -I $(top_srcdir) $< -o $@
- $(SED) -i -e 's/Time-&-Date/Time-\&-Date/g' $@
+ $(MAKEINFO) $(AM_MAKEINFOFLAGS) --docbook -I $(top_srcdir) $< -o - \
+ | $(SED) 's/Time-&-Date/Time-\&-Date/g' > $@
docbookdir = $(docdir)
docbook_DATA = doc/pspp.xml