Oh, and please don't take this as an application for becoming the next tagmanager expert :D.
Too late, it's you now :-P.
I fixed the warnings and noticed a few more of `-Wsign-compare` and `-Wunused-variable` warnings which were introduced in some past commits so fixed these too while there.
map_C_old_parser is used for Ferite and GLSL according to its comment. Ferite is gone and GLSL used the normal C parser, so I guess this whole map entry can be removed?
Yes. And thanks to this we don't need `COMMON_C` and `COMMON_C_NEW_PARSER` as separate defines so I removed `COMMON_C_NEW_PARSER` and moved the entries directly to `COMMON_C`.