attempt to update git_version.h and lib/Config_git.pl in
concurrent processes.
.PHONY: all translators utilities
-lib/Config_git.pl git_version.h: $(MINIPERL_EXE) make_patchnum.pl
+# Both git_version.h and lib/Config_git.pl are built
+# by make_patchnum.pl.
+git_version.h: lib/Config_git.pl
+
+lib/Config_git.pl: $(MINIPERL_EXE) make_patchnum.pl
$(MINIPERL) make_patchnum.pl
# make sure that we recompile perl.c if the git version changes