Remove dex cache string from mirror::Class.

The compiled code does not need it anymore.

Test: test-art-host test-art-target
Change-Id: I71c08ce12d450ab2b2cd018330d42a8b8c9e3da2
diff --git a/runtime/image.cc b/runtime/image.cc
index 52c9f4e..2ef60c3 100644
--- a/runtime/image.cc
+++ b/runtime/image.cc
@@ -25,7 +25,7 @@
 namespace art {
 
 const uint8_t ImageHeader::kImageMagic[] = { 'a', 'r', 't', '\n' };
-const uint8_t ImageHeader::kImageVersion[] = { '0', '3', '3', '\0' };
+const uint8_t ImageHeader::kImageVersion[] = { '0', '3', '4', '\0' };  // mirror::Class update
 
 ImageHeader::ImageHeader(uint32_t image_begin,
                          uint32_t image_size,