Make function pointers implement traits for up to 12 parameters

(12 was chosen to be consistent with what we do for tuples)

Fixes #28559

Author: Manishearth

src/libcore/ptr.rs

@@ -385,6 +385,13 @@ fnptr_impls_args! { A, B }
 fnptr_impls_args! { A, B, C }
 fnptr_impls_args! { A, B, C, D }
 fnptr_impls_args! { A, B, C, D, E }
+fnptr_impls_args! { A, B, C, D, E, F }
+fnptr_impls_args! { A, B, C, D, E, F, G }
+fnptr_impls_args! { A, B, C, D, E, F, G, H }
+fnptr_impls_args! { A, B, C, D, E, F, G, H, I }
+fnptr_impls_args! { A, B, C, D, E, F, G, H, I, J }
+fnptr_impls_args! { A, B, C, D, E, F, G, H, I, J, K }
+fnptr_impls_args! { A, B, C, D, E, F, G, H, I, J, K, L }
 
 // Comparison for pointers
 #[stable(feature = "rust1", since = "1.0.0")]