optionalize max_age
diff --git a/config.m4 b/config.m4
index 86f1564..2846781 100644
--- a/config.m4
+++ b/config.m4
@@ -94,7 +94,6 @@
src/core/lib/channel/handshaker_registry.c \
src/core/lib/channel/http_client_filter.c \
src/core/lib/channel/http_server_filter.c \
- src/core/lib/channel/max_age_filter.c \
src/core/lib/channel/message_size_filter.c \
src/core/lib/compression/compression.c \
src/core/lib/compression/message_compress.c \
@@ -314,6 +313,7 @@
src/core/ext/census/resource.c \
src/core/ext/census/trace_context.c \
src/core/ext/census/tracing.c \
+ src/core/ext/filters/max_age/max_age_filter.c \
src/core/plugin_registry/grpc_plugin_registry.c \
src/boringssl/err_data.c \
third_party/boringssl/crypto/aes/aes.c \
@@ -638,6 +638,7 @@
PHP_ADD_BUILD_DIR($ext_builddir/src/core/ext/filters/client_channel/resolver/dns/native)
PHP_ADD_BUILD_DIR($ext_builddir/src/core/ext/filters/client_channel/resolver/sockaddr)
PHP_ADD_BUILD_DIR($ext_builddir/src/core/ext/filters/load_reporting)
+ PHP_ADD_BUILD_DIR($ext_builddir/src/core/ext/filters/max_age)
PHP_ADD_BUILD_DIR($ext_builddir/src/core/ext/transport/chttp2/alpn)
PHP_ADD_BUILD_DIR($ext_builddir/src/core/ext/transport/chttp2/client)
PHP_ADD_BUILD_DIR($ext_builddir/src/core/ext/transport/chttp2/client/insecure)