zfp package: ensure openmp variant is processed (#24221)

* zfp: several package improvements

- add variants for build targets, language bindings, backends
- ensure selected variants are compatible with zfp version
- point to GitHub (not LLNL) tar balls
- add dependencies
- update link to homepage
- add maintainers

* zfp: address suggestions by Spack team

- use conflicts() instead of raising exceptions
- use define() and define_from_variant() where applicable

* Apply suggestions from code review

Co-authored-by: Massimiliano Culpo <massimiliano.culpo@gmail.com>

* Fix ZFP OpenMP build.

Co-authored-by: Massimiliano Culpo <massimiliano.culpo@gmail.com>

var/spack/repos/builtin/packages/zfp/package.py

@@ -93,6 +93,7 @@ def cmake_args(self):
             self.define_from_variant('BUILD_CFP', 'c'),
             self.define_from_variant('BUILD_ZFPY', 'python'),
             self.define_from_variant('BUILD_ZFORP', 'fortran'),
+            self.define_from_variant('ZFP_WITH_OPENMP', 'openmp'),
             self.define_from_variant('ZFP_WITH_CUDA', 'cuda'),
             self.define('ZFP_BIT_STREAM_WORD_SIZE',
                         spec.variants['bsws'].value),