Sort tests.

test/libsolidity/semanticTests/modifiers/function_modifier_overriding.sol

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+contract A {
+    function f() public mod returns (bool r) {
+        return true;
+    }
+
+    modifier mod virtual {
+        _;
+    }
+}
+
+
+contract C is A {
+    modifier mod override {
+        if (false) _;
+    }
+}
+
+// ----
+// f() -> false