CBMConvert does not build under C 23

[paulscottrobson]

Occurs on Ubuntu 25.04 but likely on any modern distribution.

CBMConvert does not build because util.h defines its own version of the bool type, which is in most C compilers after C 23 (I think).

To reproduce ; build on a modern compiler.

Fix:

My simple fix was simply to remove the bool definition from util.h in cbmconvert, it then compiles (as does everything else). The submodule repository hasn't been touched for 7 years and there's one seemingly dead fork, so possibly just bring it in to the repo rather than it being a submodule.

Adding -std=c99 may well work.