Refix for diagnosis on expected expressions.

test/ref/bug1889-missing-identifier.c

@@ -3,6 +3,8 @@
 int enum { a } x;
 inline enum { b };
 
+_Static_assert();
+
 int main(void)
 {
     return 0;

test/ref/bug1889-missing-identifier.cref

@@ -1,3 +1,4 @@
 bug1889-missing-identifier.c:3: Error: Identifier or ';' expected after declaration specifiers
 bug1889-missing-identifier.c:3: Warning: Implicit 'int' is an obsolete feature
 bug1889-missing-identifier.c:4: Error: Declaration specifier or identifier expected
+bug1889-missing-identifier.c:6: Error: Expression expected