Merge pull request #9118 from ethereum/develop

Merge develop into breaking.

test/libsolidity/syntaxTests/inheritance/override/private_state_variable.sol

@@ -0,0 +1,9 @@
+contract C1 {
+  function f() external pure returns(int) { return 42; }
+}
+
+contract C is C1 {
+   int override f;
+}
+// ----
+// TypeError: (96-110): Override can only be used with public state variables.