Removed the non-existing-in-C "struct/union scope" for structs/unions.

Fixed handling of struct/union field declarations without identifiers, which do nothing.

test/val/bug1437.c

@@ -0,0 +1,35 @@
+
+/* bug #1437 enum declaration in a struct/union is invisible in the scope where the struct/union is declared */
+
+struct nodelist1 {
+    struct {
+        enum { DEAD1, LIVE1, ONCE1, TWICE1 } live1;
+    } s;
+} firstnode1 = {ONCE1};
+
+enum nodestate2 { DEAD2, LIVE2, ONCE2, TWICE2 } live2;
+
+union nodelist2 {
+    enum nodestate2 live2;
+} firstnode2 = { {TWICE2} };
+
+struct T {
+    int I;
+    int;
+    enum E {
+        I
+    };
+};
+
+int failures = 0;
+
+int main (void)
+{
+    if (firstnode1.s.live1 != ONCE1) {
+        ++failures;
+    }
+    if (firstnode2.live2 != TWICE2) {
+        ++failures;
+    }
+    return failures;
+}