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/vc/package.py

@@ -35,11 +35,7 @@ class Vc(CMakePackage):
     version('1.2.0', 'a5236df286b845d2fee5ef1e4d27549f')
     version('1.1.0', 'e354c1e3ea1d674b6f2af9c6fd230d81')
 
-    variant('debug', default=False)
-
-    def build_type(self):
-        spec = self.spec
-        if '+debug' in spec:
-            return 'Debug'
-        else:
-            return 'Release'
+    variant('build_type', default='RelWithDebInfo',
+            description='The build type to build',
+            values=('Debug', 'Release', 'RelWithDebug',
+                    'RelWithDebInfo', 'MinSizeRel'))