make the Makefile in the doc/ dir more portable (%.dvi: %.tex is GNU make only, well at least it doesn't work on NetBSD make)

doc/Makefile

@@ -1,18 +1,25 @@
 # window manager improved 2 user guide
-SRC = guide_en.tex wmii.tex
-Odvi = ${SRC:.tex=.dvi}
-Opdf = ${SRC:.tex=.pdf}
-Ohtml = ${SRC:.tex=.html}
 
-all: ${Odvi} ${Opdf} #${Ohtml}
-%.dvi: %.tex
+SRC = guide_en.tex wmii.tex
+DVI = ${SRC:.tex=.dvi}
+PDF = ${SRC:.tex=.pdf}
+HTML = ${SRC:.tex=.html}
+
+all: ${DVI} ${PDF} #${HTML}
+
+.SUFFIXES: .tex .dvi .pdf .html
+
+.tex.dvi:
 	latex -interaction=batchmode $<
 	latex -interaction=batchmode $<
-%.pdf: %.tex
+
+.tex.pdf:
 	pdflatex $<
 	pdflatex $<
-%.html: %.tex
+
+.tex.html:
 	latex2html $<
+
 clean:
 	rm -f *.pdf *.dvi *.log *.aux *.out *.toc
 	rm -rf guide_en