[LyX/master] Start reporting missing citations and broken references in LaTeX build.

[Joel Kulesza]

> On Mar 14, 2020, at 08:39, Jürgen Spitzmüller <spitz at lyx.org> wrote:
> 
> Am Samstag, den 14.03.2020, 08:25 -0600 schrieb Joel Kulesza:
>> One thing that's been on my mind for a while is coloring the broken
>> elements differently than default; however, it was not clear to me
>> how to achieve that in a straightforward way.
> 
> I've done this as well. See
> https://www.lyx.org/trac/ticket/11503
> 
> Jürgen

Awesome, thank you again!

Joel