Fix shadowing struct types by struct member names

test/libsolidity/syntaxTests/errors/error_param_type_shadowed_by_builtin_type_used_as_param_name.sol

@@ -0,0 +1,5 @@
+contract C {
+    error E(int bytes, bytes x);
+}
+// ----
+// ParserError 2314: (29-34): Expected ',' but got 'bytes'

test/libsolidity/syntaxTests/errors/error_param_type_shadowed_by_param_name.sol

@@ -0,0 +1,12 @@
+contract C {
+    enum EnumType {A, B, C}
+
+    struct StructType {
+        uint x;
+    }
+
+    error E1(StructType StructType);
+    error E2(EnumType EnumType);
+    error E3(EnumType StructType, StructType EnumType);
+}
+// ----