Added some array testcases

test/arrays/check_error/redefined_dimension.cvc

@@ -0,0 +1,5 @@
+int n = 1;
+void foo() {
+    // n is NOT 1 here since the name "n" is first redefined as array
+    int[n] n;
+}

test/arrays/check_error/shadowed_dimension.cvc

@@ -0,0 +1 @@
+void foo(int[a] a) {}  // "a" is redefined