Accept empty struct member decls

struct S { /*nothing*/; int a; };

is an acceptable struct declaration, there may be stray semicolons
in the member list.

tccgen.c

@@ -3250,7 +3250,10 @@ static void struct_decl(CType *type, AttributeDef *ad, int u)
             offset = 0;
             flexible = 0;
             while (tok != '}') {
-                parse_btype(&btype, &ad1);
+                if (!parse_btype(&btype, &ad1)) {
+		    skip(';');
+		    continue;
+		}
                 while (1) {
                 extra_bytes = 0;
 		    if (flexible)

tests/tcctest.c

@@ -642,6 +642,11 @@ union union2 {
 
 struct struct1 st1, st2;
 
+struct empty_mem {
+    /* nothing */ ;
+    int x;
+};
+
 int main(int argc, char **argv)
 {
     string_test();