[Makefile] more accurate dependencies for generated test file

Makefile

@@ -2345,7 +2345,8 @@ GENERATED_TESTS:=
 endif
 
 ifneq ("$(HAS_UNIX2DOS)","no")
-tests/spec/preprocess_dos.c: tests/spec/preprocess_dos.c.in
+tests/spec/preprocess_dos.c: tests/spec/preprocess_dos.c.in \
+                             Makefile share/Makefile.config.in
 	$(SED) -e "s|@UNIX2DOS@|$(UNIX2DOS)|g" \
                -e "s|@DONTRUN@||g" \
                $< > $@