CMake P4EST_BUILD_EXAMPLES flag

[dutkalex]

CMake P4EST_BUILD_EXAMPLES flag

Just adds this flag to give the opportunity to downstream projects to disable this and save on build times.

[cburstedde]

Thanks! We had previously set examples to be always built, but it's fine to add this option as you suggest with default ON. While we're at it:

• Can we make an analogous change in libsc, double-checking that the CMake example logic looks the exact same in both libraries?
• I would not build the tests by default, only on make check, as with autoconf. Is this possible with CMake (and again, for both p4est and sc)?

[dutkalex]

• Can we make an analogous change in libsc, double-checking that the CMake example logic looks the exact same in both libraries?

Yes that seems reasonable. I can open a quick PR on libsc too.

• I would not build the tests by default, only on make check, as with autoconf. Is this possible with CMake (and again, for both p4est and sc)?

That I do not know. Maybe it can be done, but no obvious solution comes to my mind right now...

[cburstedde]

• Can we make an analogous change in libsc, double-checking that the CMake example logic looks the exact same in both libraries?

Yes that seems reasonable. I can open a quick PR on libsc too.

Sounds great! There seems to be just some small glitch with the CI. And please add your author file to the docs, and a line to the doc/release_notes.txt

• I would not build the tests by default, only on make check, as with autoconf. Is this possible with CMake (and again, for both p4est and sc)?

That I do not know. Maybe it can be done, but no obvious solution comes to my mind right now...

Thanks; then we let this remain as is for now.