fixed a buffer copying bug (can't find buffer mmap handling examples)
fixed a buffer copying bug (can't find buffer mmap handling examples)

slact/nginx_http_push_module,flybird119/nginx_http_push_module,lzpfmh/nginx_http_push_module,jedisct1/nginx_http_push_module,Kronuz/nginx_http_push_module,slact/nginx_http_push_module,lzpfmh/nginx_http_push_module,Kronuz/nginx_http_push_module,h0x91b/nginx_http_push_module,Kronuz/nginx_http_push_module,flybird119/nginx_http_push_module,h0x91b/nginx_http_push_module,slact/nginx_http_push_module,lzpfmh/nginx_http_push_module,lzpfmh/nginx_http_push_module,h0x91b/nginx_http_push_module,flybird119/nginx_http_push_module,h0x91b/nginx_http_push_module,jedisct1/nginx_http_push_module,flybird119/nginx_http_push_module,slact/nginx_http_push_module,jedisct1/nginx_http_push_module