make build fail when OpenCSG < 1.3.2 or CGAL < 3.9

[donbright]

mailing list has had several recent bug reports that were fixed by using updated library versions.

this patch will make the build itself fail. it would be better to detect the version within the build script, but that is rather difficult in qmake.

this will make the 'libcgal' packages on most linux versions unusable (outdated) with openscad, but it is relatively simple to build + install CGAL from source on linux.

the same is true of OpenCSG - 1.3.2 only came out in late late 2011. but it is also relatively easy to build and install on linux.

[kintel]

I find it a bit harsh to just fail. There might be reasons for using older versions.
.. but for release builds it would make sense I think.

[kintel]

Did you close this for a reason? The idea is good, I'm just unsure about when to enforce this behavior.

[donbright]

i was deleting all my old junk branches to clean things up, and i guess it closed this automatically?

yeah, i dont know when to do it either or how to do it.

i dont like having it in the source code either. i think it belongs inside the build system.

cmake it wouldn't be too bad, they have those VERSION functions you are already using. it could throw up a warning, and then allow people to pass a '-DFORCE_OLD_LIBRARY' option with old versions if they wanted to.

qmake, i have no idea how to do it in qmake. i guess there is probably a way some how. but i dont think it would be pretty.