There is no soname bump, but I built root-6.34.02-2 with openmp and llvm-libs
19.1.6, but the LLVM upgrade was faster than me uploading the root package.

- remove unnecessary overrides for compiler flags
- move cmake flags into a local bash array
- eliminate redundant cmake settings file for cuda build
- revise dependencies

- change indentation to 2 spaces
- remove unnecessary quotes
- switch license to SPDX
- use common optdepends for both split packages

Related upstream commit https://github.com/root-project/root/commit/ed7a6080d8bd39d8355555d7fc33877396846e34.
Related Todo list https://archlinux.org/todo/move-to-pcre2/.

The options minuit2_omp and minuit2_mpi were disabled in commit
22a233ed

root does not support external openui5 for installation purposes:
https://github.com/root-project/root/blob/v6-30-04/cmake/modules/SearchInstalledSoftware.cmake#L2048-L2055

Switching builtin_openui5 to ON avoids downloading during the build.

Ninja builds faster than GNU Make and we don't like to wait.

* Release 6.30 added support for GCC 13, so remove GCC 12 dep.
* Add flag to disable non-supported GSL.