fix Makefile dist target

the sparse.c and sscan.c files are now committed in src dir

Author: pdowler

Diff for: Makefile

@@ -227,7 +227,7 @@ else
 	@$(missing) flex $< $@
 endif
 
-dist : clean sparse.c sscan.c
+dist : clean
 	find . -name '*~' -type f -exec rm {} \;
 	cd .. && tar --transform s/$(SRC_DIR)/pgsphere-$(PGSPHERE_VERSION)/ --exclude CVS --exclude .git -czf pgsphere-$(PGSPHERE_VERSION).tar.gz $(SRC_DIR) && cd -