Fix documentation installation. This is the real 0.99.beta15 release.

doc/Makefile.am

@@ -43,6 +43,7 @@ clean-local:
 
 install-data-local:
 if BUILD_DOCUMENTATION
+	mkdir -p $(DESTDIR)$(datadir)/doc
 	ln -s libcaca-dev $(DESTDIR)$(datadir)/doc/libcucul-dev
 	$(mkinstalldirs) $(DESTDIR)$(datadir)/doc/libcaca-dev/html
 	cp `find html -name '*.html' -o -name '*.gif' -o -name '*.png'` \
@@ -59,4 +60,5 @@ endif
 
 uninstall-local:
 	rm -f $(DESTDIR)$(datadir)/doc/libcucul-dev
+	rmdir $(DESTDIR)$(datadir)/doc 2>/dev/null || true