Split calldataEncodedSize into calldataEncodedSize, calldataEncodedTailSize and calldataHeadSize and fix all usages.

test/libsolidity/semanticTests/abiEncoderV2/calldata_struct_member_offset.sol

@@ -0,0 +1,23 @@
+pragma experimental ABIEncoderV2;
+
+contract C {
+    struct A {
+        uint256 a;
+        uint256[] b;
+    }
+    struct B {
+        A a;
+        uint256 b;
+    }
+    function g(B calldata b) external pure returns(uint256) {
+        return b.b;
+    }
+    function f() public view returns(uint256, uint256) {
+        uint256[] memory arr = new uint256[](20);
+        arr[0] = 31; arr[2] = 84;
+        B memory b = B(A(420, arr), 11);
+        return (b.b, this.g(b));
+    }
+}
+// ----
+// f() -> 11, 11