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/pegtl/package.py

@@ -39,12 +39,3 @@ class Pegtl(CMakePackage):
     version('develop', git='https://github.com/taocpp/PEGTL', branch='master')
     version('2.1.4', 'e5288b6968e6e910287fce93dc5557bf')
     version('2.0.0', 'c772828e7188459338a920c21f9896db')
-
-    variant('debug', default=False, description='Build debug version')
-
-    def build_type(self):
-        spec = self.spec
-        if '+debug' in spec:
-            return 'Debug'
-        else:
-            return 'Release'