irssi: use .diff for manually applied patch

So that all manually applied patches have the same suffix.

%ci:no-build

packages/irssi/build.sh

@@ -27,7 +27,7 @@ termux_step_pre_configure() {
 	sed -e "s|@TERMUX_PREFIX@|$TERMUX_PREFIX|g" \
 		-e "s|@TERMUX_PERL_VERSION@|$perl_version|g" \
 		-e "s|@TERMUX_PERL_TARGET@|${TERMUX_ARCH}-android|g" \
-		$TERMUX_PKG_BUILDER_DIR/perl_config_support.patch.txt | \
+		$TERMUX_PKG_BUILDER_DIR/perl_config_support.diff | \
 		patch -p1
 	autoconf
 	TERMUX_PKG_EXTRA_CONFIGURE_ARGS+=" --with-perl-lib=$TERMUX_PREFIX/lib/perl5/site_perl/$perl_version/${TERMUX_ARCH}-android"