Add a test that triggers the out-of-bounds ICE.

Add a test that has the right input to trigger an out-of-bounds
error when in MIR the local_decls and the normalized_input_tys don't
match in amount.

src/test/ui/mir/issue-83499-input-output-iteration-ice.rs

@@ -0,0 +1,10 @@
+// Test that when in MIR the amount of local_decls and amount of normalized_input_tys don't match
+// that an out-of-bounds access does not occur.
+#![feature(c_variadic)]
+
+fn main() {}
+
+fn foo(_: Bar, ...) -> impl {}
+//~^ ERROR only foreign or `unsafe extern "C" functions may be C-variadic
+//~| ERROR cannot find type `Bar` in this scope
+//~| ERROR at least one trait must be specified