Add universal build_type variant to CMakePackage (#4797)

* Add universal build_type variant to CMakePackage
* Override build_type in some packages with different possible values
* Remove reference to no longer existent debug variant
* Update CBTF packages with new build_type variant
* Keep note on build size of LLVM

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

@@ -50,6 +50,9 @@ class Eccodes(CMakePackage):
             description="Enable OpenMP threads")
     variant('memfs', default=False,
             description="Memory based access to definitions/samples")
+    variant('build_type', default='RelWithDebInfo',
+            description='The build type to build',
+            values=('Debug', 'Release', 'RelWithDebInfo', 'Production'))
 
     depends_on('netcdf', when='+netcdf')
     depends_on('openjpeg', when='+jpeg')