Add Makefile in doc/ for generating doc for MacOS builds

using macports

anyway brew fails to install the static libraries...

doc/Makefile

@@ -0,0 +1,56 @@
+CP = cp
+
+all:
+	@echo "nothing to do..."
+
+# fetch files from macports
+MACPORTSPATH = $(shell which port | sed 's;/bin/port$$;;' )
+DOCPATH = $(MACPORTSPATH)/share/doc
+PACKAGES = libsdl2 libsdl2_image jpeg tiff webp
+PACKAGSS += libsdl2_ttf freetype
+PACKAGES += libpng zlib lua
+
+READMES = $(PACKAGES:%=README-%.txt)
+
+macports:	$(READMES)
+
+clean:
+	$(RM) $(READMES)
+
+#	for p in $(PACKAGES) ; do \
+	  echo $(DOCPATH)/$$p ; \
+	  ls $(DOCPATH)/$$p ; \
+	done
+
+README-libsdl2.txt:	$(DOCPATH)/libsdl2/README-SDL.txt $(DOCPATH)/libsdl2/COPYING.txt
+	p=$(@:README-%.txt=%) ; echo "$$p $$(port info --version $$p)" > $@
+	cat $(DOCPATH)/libsdl2/README-SDL.txt >> $@
+	cat $(DOCPATH)/libsdl2/COPYING.txt >> $@
+
+README-libsdl2_image.txt:
+	p=$(@:README-%.txt=%) ; echo "$$p $$(port info --version $$p)" > $@
+	cat $(DOCPATH)/libsdl2_image/COPYING.txt >> $@
+
+README-tiff.txt:	$(DOCPATH)/tiff/COPYRIGHT
+	p=$(@:README-%.txt=%) ; echo "$$p $$(port info --version $$p)" > $@
+	echo "" >> $@
+	cat $(DOCPATH)/tiff/COPYRIGHT >> $@
+
+README-lua.txt: $(DOCPATH)/lua/README $(DOCPATH)/lua/COPYRIGHT
+	$(CP) $< $@
+	echo "" >> $@
+	cat $(DOCPATH)/lua/COPYRIGHT >> $@
+
+README-libpng.txt:	$(DOCPATH)/libpng/LICENSE
+	echo "libpng $$(port info --version libpng)" > $@
+	echo "" >> $@
+	echo "License :" >> $@
+	echo "" >> $@
+	cat $< >> $@
+
+README-%.txt: $(DOCPATH)/%/README
+	p=$(@:README-%.txt=%) ; echo "$$p $$(port info --version $$p)" > $@
+	echo "" >> $@
+	cat $< >> $@
+	f=$(DOCPATH)/$(@:README-%.txt=%)/COPYING ; \
+	  if [ -f "$$f" ] ; then echo "License :" >> $@ ; cat "$$f" >> $@ ; fi