replace pinentry.el with pinentry submodule

.gitmodules

@@ -214,3 +214,6 @@
 [submodule "site-lisp/crontab-mode"]
 	path = site-lisp/crontab-mode
 	url = https://github.com/emacs-pe/crontab-mode.git
+[submodule "site-lisp/pinentry"]
+	path = site-lisp/pinentry
+	url = https://github.com/ueno/pinentry-el.git