New documentation targets (pdf & txt)

[Derek Robert Price]

Here are several generic rules for creation of PDF and ASCII output from
*.texinfo files in case anyone is interested.  Both rules use makeinfo
so they shouldn't create any new dependencies and the input and output
file sets are the same as for *.info files, except do a s/\.info$/.pdf/
or s/\.info$/.txt, respectively, so it should be easy to construct the
target and dependency list for pdf: and txt: targets.  Glancing at the
new 1.5 *.info targets, I think these may be slightly out of date - it
looks like they should probably use
$(AM_MAKEINFOFLAGS) & $(MAKEINFOFLAGS) instead of some of the makeinfo
arguments - but the targets are modeled after one of the 1.4X targets.
I've been using them both rule sets successfully with the
CVS distribution for some time now:

# texinfo based targets automake neglects to include
.texinfo.pdf:
        TEXINPUTS=$(srcdir):$$TEXINPUTS \
          MAKEINFO='$(MAKEINFO) -I $(srcdir)' $(TEXI2DVI) --pdf $<
.txi.pdf:
        TEXINPUTS=$(srcdir):$$TEXINPUTS \
          MAKEINFO='$(MAKEINFO) -I $(srcdir)' $(TEXI2DVI) --pdf $<
.texi.pdf:
        TEXINPUTS=$(srcdir):$$TEXINPUTS \
          MAKEINFO='$(MAKEINFO) -I $(srcdir)' $(TEXI2DVI) --pdf $<

.texinfo.txt:
        TEXINPUTS=$(srcdir):$$TEXINPUTS \
          MAKEINFO='$(MAKEINFO) -I $(srcdir)' $(MAKEINFO) $<
--no-headers -o $@
.txi.txt:
        TEXINPUTS=$(srcdir):$$TEXINPUTS \
          MAKEINFO='$(MAKEINFO) -I $(srcdir)' $(MAKEINFO) $<
--no-headers -o $@
.texi.txt:
        TEXINPUTS=$(srcdir):$$TEXINPUTS \
          MAKEINFO='$(MAKEINFO) -I $(srcdir)' $(MAKEINFO) $<
--no-headers -o $@

Derek