[PATCH] debuginfod: Check result of calling MHD_add_response_header.

[Frank Ch. Eigler]

Hi -

> Although unlikely the MHD_add_response_header can fail for
> various reasons.  If it fails something odd is going on.
> So check we can actually add a response header before using
> the response.

ISTM it is okay to send the response object (the body), even if
something goes wrong with adding optional headers later.


- FChE