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/vecgeom/package.py

@@ -36,17 +36,8 @@ class Vecgeom(CMakePackage):
     version('0.3.rc', git='https://gitlab.cern.ch/VecGeom/VecGeom.git',
             tag='v0.3.rc')
 
-    variant('debug', default=False, description='Build debug version')
-
     depends_on('cmake@3.5:', type='build')
 
-    def build_type(self):
-        spec = self.spec
-        if '+debug' in spec:
-            return 'Debug'
-        else:
-            return 'Release'
-
     def cmake_args(self):
         options = [
             '-DBACKEND=Scalar',