subversion: Fix building with unified headers

packages/subversion/build.sh

@@ -5,3 +5,7 @@ TERMUX_PKG_SRCURL=http://apache.mirrors.spacedump.net/subversion/subversion-${TE
 TERMUX_PKG_SHA256=8a4fc68aff1d18dcb4dd9e460648d24d9e98657fbed496c582929c6b3ce555e5
 TERMUX_PKG_DEPENDS="apr, apr-util, serf, libexpat, libsqlite"
 TERMUX_PKG_EXTRA_CONFIGURE_ARGS="--without-sasl --without-libmagic"
+
+termux_step_pre_configure() {
+	CPPFLAGS+=" -std=c11"
+}