C++: Add upgrade and downgrade scripts

cpp/downgrades/e38346051783182ea75822e4adf8d4c6a949bc37/builtintypes.ql

@@ -0,0 +1,9 @@
+class BuiltinType extends @builtintype {
+  string toString() { none() }
+}
+
+from BuiltinType id, string name, int kind, int new_kind, int size, int sign, int alignment
+where
+  builtintypes(id, name, kind, size, sign, alignment) and
+  if kind = 63 then /* @errortype */ new_kind = 1 else new_kind = kind
+select id, name, new_kind, size, sign, alignment

cpp/downgrades/e38346051783182ea75822e4adf8d4c6a949bc37/derivedtypes.ql

@@ -0,0 +1,9 @@
+class Type extends @type {
+  string toString() { none() }
+}
+
+from Type type, string name, int kind, int new_kind, Type type_id
+where
+  derivedtypes(type, name, kind, type_id) and
+  if kind = 11 then /* @gnu_vector */ new_kind = 5 else new_kind = kind
+select type, name, new_kind, type_id

cpp/downgrades/e38346051783182ea75822e4adf8d4c6a949bc37/upgrade.properties

@@ -0,0 +1,5 @@
+description: Arm scalable vector type support
+compatibility: backwards
+builtintypes.rel: run builtintypes.qlo
+derivedtypes.rel: run derivedtypes.qlo
+tupleelements.rel: delete

cpp/ql/lib/upgrades/9baef67d1ffc1551429dbe1c1130815693e28218/upgrade.properties

@@ -0,0 +1,2 @@
+description: Arm scalable vector type support
+compatibility: full