prohibit_generics: update has_err for consts

src/librustc_typeck/astconv.rs

@@ -2440,6 +2440,7 @@ pub fn prohibit_generics<'a, T: IntoIterator<Item = &'a hir::PathSegment<'a>>>(
                             continue;
                         }
                         err_for_ct = true;
+                        has_err = true;
                         (ct.span, "const")
                     }
                 };