* doc/Makefile.am: Include $(top_srcdir)/build-aux/tex.mk.
	(TEXI2DVI_FLAGS): Append -I $(DOC_SRCDIR), -I $(OUTPUTS_SRCDIR),
	-I $(SPLIT_OUTPUTS_SRCDIR), -I $(IMG_SRCDIR) and -I
	$(SPLIT_EXAMPLES_SRCDIR).
	(technical_TEXINPUTS, tutorial_TEXINPUTS)
	(white_paper_TEXINPUTS, ref_guide_TEXINPUTS):
	Remove variables.
	($(TECHNICAL_PDF), $(TUTORIAL_PDF))
	($(WHITE_PAPER_PDF), $(REF_GUIDE_PDF)):
	Reduce these rules to a list of extra dependencies and let the
	generic tex-to-pdf rule do the job.
	($(WHITE_PAPER_HTML)): Adjust rule.