wp_ob_end_flush_all() tries to destroy non-destroyable output buffers

[dd32]

wp_ob_end_flush_all() currently tries to flush & destroy every PHP Output buffer that is enabled on the current installation.
However, not every type of PHP Output buffer can be destroyed, which will cause a PHP Notice when attempts to do so are made.
An example of this is PHP extensions such as New Relic, or PHP output buffers created with the $erase flag set to false in ob_start()

An example is when New Relic is installed on a host, also ​see New Relics FAQ entry on the issue.

( ! ) Notice: ob_end_flush(): failed to send buffer of New Relic auto-RUM (1) in ../trunk/wp-includes/functions.php on line 2641
Call Stack
#	Time	Memory	Function	Location
1	0.8510	4328360	shutdown_action_hook( )	../load.php:0
2	0.8510	4328440	do_action( )	../load.php:556
3	0.8510	4329856	call_user_func_array ( )	../plugin.php:406
4	0.8510	4329888	wp_ob_end_flush_all( )	../plugin.php:406
5	0.8511	4330064	ob_end_flush ( )	../functions.php:2641

Somewhat similar to #18239
I'm not sure of what the ideal solution for this would be for WordPress, but wanted to record the issue being known.

[dd32]

One option is to just silence the PHP Notice to get the message out of developers faces.. (Ignore the extra ob in the diff..)

[chriscct7]

Extra item in the docblock