possible bug regarding dead keys + accent

[Filipe Silva]

Hi gentleman, 

I believe I discovered a bug regarding the dead acute + c combination, which would have to produce a ç under my setup.

The thread started here

http://lists.gnu.org/archive/html/help-gnu-emacs/2017-07/msg00070.html

basically, I setup my machine like described here: https://emacs.stackexchange.com/q/33968/12585

In all applications, in the terminal, in gvim, in scite, in all browsers, <deadacute> + c produce ç, but not in emacs. 

But if I launch emacs with this line: `LANG=C emacs`, then it all works. 

But why does it works? Would it be a bug?