Replace .3tiff man page suffix with standard .3

Index: man/Makefile.in
--- man/Makefile.in.orig
+++ man/Makefile.in
@@ -500,7 +500,7 @@ install-man3: $(dist_man3_MANS)
 	  if test -f $$p; then d=; else d="$(srcdir)/"; fi; \
 	  echo "$$d$$p"; echo "$$p"; \
 	done | \
-	sed -e 'n;s,.*/,,;p;h;s,.*\.,,;s,^[^3][0-9a-z]*$$,3,;x' \
+	sed -e 'n;s,.*/,,;p;h;s,.*\.,,;s,^.[0-9a-z]*$$,3,;x' \
 	      -e 's,\.[0-9a-z]*$$,,;$(transform);G;s,\n,.,' | \
 	sed 'N;N;s,\n, ,g' | { \
 	list=; while read file base inst; do \
