xbps-src: make internal var UPPERCASE.

xbps-src/shutils/pkgtarget_funcs.sh.in

@@ -124,7 +124,12 @@ install_pkg()
 	fi
 	trap - INT
 
-	[ "$install_destdir_target" = "yes" ] && return 0
+	# If only installation to destdir, return.
+	if [ -n "$DESTDIR_ONLY_INSTALL" ]; then
+		if [ -d "$wrksrc" -a -z "$KEEP_WRKSRC" ]; then
+			remove_tmpl_wrksrc $wrksrc
+		fi
+	fi
 
 	# Stow package into masterdir.
 	stow_pkg_handler stow

xbps-src/xbps-src.sh.in

@@ -369,8 +369,7 @@ install|install-destdir)
 		_pkgname=$(basename_cwd)
 	fi
 	setup_tmpl ${_pkgname}
-	install_destdir_target=no
-	[ "$target" = "install-destdir" ] && install_destdir_target=yes
+	[ "$target" = "install-destdir" ] && DESTDIR_ONLY_INSTALL=1
 
 	_ORIGINPKG="${_pkgname}"
 	if [ -z "$in_chroot" -a -z "$base_chroot" ]; then