[LyX/master] Add default TransformID enum value

[Jean-Marc Lasgouttes]

Le 26/11/2020 à 22:38, Pavel Sanda a écrit :
>> I'm not an expert in build systems, so my patch doing this will require some
>> correction.
> 
> Autotools looks fine on a first sight, JMarc might have some comment.

I have removed the unneeded autoconf parts and remove the machinery to 
build a boost library (only regex needed it). The gain is only 2M out of 23.

What remains to be done:

- remove last remnants of cmake support code in 3rdparty/boost

- get rid of support/regex.h

- Use system boost by default on autotools (this was needed because of 
interactions between stdlib-debug and system boost).

JMarc