test: Add xfail-win32 to two debug-info tests

Author: klutzy

src/test/debug-info/by-value-self-argument-in-trait-impl.rs

@@ -8,6 +8,7 @@
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.
 
+// xfail-win32: FIXME (#10474)
 // xfail-android: FIXME(#10381)
 
 #[feature(managed_boxes)];

src/test/debug-info/var-captured-in-nested-closure.rs

@@ -8,6 +8,7 @@
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.
 
+// xfail-win32: FIXME #10474
 // xfail-android: FIXME(#10381)
 
 // compile-flags:-Z extra-debug-info