pkg_install: Add an explicit dummy DEINSTALL script.

Even with DEINSTALL_SRC set empty, changes in the pkgsrc infrastructure over
the past few years will now create a dynamic +DEINSTALL script regardless,
and while only containing "exit 0", may have a #! using a shell from pkgsrc.

This can lead to upgrade issues if that shell happens to be unavailable
while pkg_install is being upgraded.  Creating our own dummy script that
explicitly uses /bin/sh avoids that problem.


(jperkin)

#!/bin/sh
#
# Dummy script to ensure pkgsrc never creates its own DEINSTALL script for
# this package that uses a pkgsrc shell, as that can cause upgrade issues.
#
exit 0

@@ -1,4 +1,4 @@
-# $NetBSD: Makefile,v 1.235 2021/06/05 14:17:32 nia Exp $
+# $NetBSD: Makefile,v 1.236 2021/11/03 13:37:25 jperkin Exp $
 
 # Notes to package maintainers:
 #
@@ -86,7 +86,7 @@
 
 PLIST_SUBST+=		PKG_DBDIR=${PKG_DBDIR}
 
-DEINSTALL_SRC=		# empty
+DEINSTALL_SRC=		${PKGDIR}/DEINSTALL
 INSTALL_SRC=		${PKGDIR}/INSTALL
 FILES_SUBST+=		PKG_DBDIR=${PKG_DBDIR}			\
 			PKG_TOOLS_BIN=${PKG_TOOLS_BIN:Q}	\