C++: Add db upgrade and downgrade scripts for repeated initializers.

Author: sashabu

cpp/downgrades/19887dbd33327fb07d54251786e0cb2578539775/old.dbscheme

@@ -0,0 +1,4 @@
+description: Revert support for repeated initializers, which are allowed in C with designated initializers.
+compatibility: backwards
+aggregate_field_init.rel: reorder aggregate_field_init.rel (int aggregate, int initializer, int field, int position) aggregate initializer field
+aggregate_array_init.rel: reorder aggregate_array_init.rel (int aggregate, int initializer, int element_index, int position) aggregate initializer element_index

cpp/downgrades/19887dbd33327fb07d54251786e0cb2578539775/semmlecode.cpp.dbscheme

@@ -0,0 +1,11 @@
+class AggregateLiteral extends @aggregateliteral {
+  string toString() { none() }
+}
+
+class Expr extends @expr {
+  string toString() { none() }
+}
+
+from AggregateLiteral al, Expr init, int index, int position
+where exprparents(init, position, al) and aggregate_array_init(al, init, index)
+select al, init, index, position

cpp/downgrades/19887dbd33327fb07d54251786e0cb2578539775/upgrade.properties

@@ -0,0 +1,15 @@
+class AggregateLiteral extends @aggregateliteral {
+  string toString() { none() }
+}
+
+class Expr extends @expr {
+  string toString() { none() }
+}
+
+class Field extends @membervariable {
+  string toString() { none() }
+}
+
+from AggregateLiteral al, Expr init, Field field, int position
+where exprparents(init, position, al) and aggregate_field_init(al, init, field)
+select al, init, field, position