Oh, sorry, the `config` file contains:

ngx_addon_name=ngx_http_file_chunks_filter_module

HTTP_MODULES="$HTTP_MODULES ngx_http_file_chunks_filter_module"

HTTP_INCS="$HTTP_INCS /usr/include/libxml2 "
CORE_LIBS="$CORE_LIBS -lxml2"

NGX_ADDON_SRCS="$NGX_ADDON_SRCS $ngx_addon_dir/ngx_http_file_chunks_filter_module.c"