Added consensus item about sorting Makefile lines.

[Carlos O'Donell]

Community,

I added the following to consensus:

https://sourceware.org/glibc/wiki/Consensus#Trivial_Bug-Fix_Changes
~~~
Anyone can commit a change to reformat a Makefile to use one value 
per line (with trailing comment) where the variable is assigned 
multiple values in one line. Such a change needs to clearly state 
(in the commit message) if any code generation changes are observed 
and the results of testing. The convenience script 
scripts/sort-makefile-lines.py is provided to sort the lines between 
the start and end markers. 
~~~

Please feel empowered to cleanup any Makefiles we are using.

I'm about to commit a cleanup to the most used Makefiles that were
partially converted as each of us was added new lines.

-- 
Cheers,
Carlos.