Add xz decompression method.

Use the method to check compressed data in debug builds.

Test: boot.oat is identical
Change-Id: Id796d4ba19c338522fc855f751bac00555029c79
diff --git a/compiler/debug/elf_debug_writer.cc b/compiler/debug/elf_debug_writer.cc
index 71422d4..e13f8be 100644
--- a/compiler/debug/elf_debug_writer.cc
+++ b/compiler/debug/elf_debug_writer.cc
@@ -134,7 +134,7 @@
   CHECK(builder->Good());
   std::vector<uint8_t> compressed_buffer;
   compressed_buffer.reserve(buffer.size() / 4);
-  XzCompress(ArrayRef<uint8_t>(buffer), &compressed_buffer);
+  XzCompress(ArrayRef<const uint8_t>(buffer), &compressed_buffer);
   return compressed_buffer;
 }