opt into box_patterns in debuginfo tests.

src/test/debuginfo/destructured-fn-argument.rs

@@ -311,6 +311,7 @@
 // lldb-command:continue
 
 #![allow(unused_variables)]
+#![feature(box_patterns)]
 #![feature(box_syntax)]
 #![omit_gdb_pretty_printer_section]
 

src/test/debuginfo/destructured-for-loop-variable.rs

@@ -153,6 +153,7 @@
 // lldb-command:continue
 
 #![allow(unused_variables)]
+#![feature(box_patterns)]
 #![feature(box_syntax)]
 #![omit_gdb_pretty_printer_section]
 

src/test/debuginfo/destructured-local.rs

@@ -244,6 +244,7 @@
 
 
 #![allow(unused_variables)]
+#![feature(box_patterns)]
 #![feature(box_syntax)]
 #![omit_gdb_pretty_printer_section]