DWARF mixed versions with LTO on MIPS

On MIPS the DWARF version is stored in 2 bytes with the `.2byte`
assembler directive.

Author: LukasWoodtli

tests/assembly/dwarf-mixed-versions-lto.rs

@@ -14,6 +14,6 @@ fn main() {
 }
 
 // CHECK: .section .debug_info
-// CHECK-NOT: {{\.(short|hword)}} 2
-// CHECK-NOT: {{\.(short|hword)}} 4
-// CHECK: {{\.(short|hword)}} 5
+// CHECK-NOT: {{\.(short|hword|2byte)}} 2
+// CHECK-NOT: {{\.(short|hword|2byte)}} 4
+// CHECK: {{\.(short|hword|2byte)}} 5