Fix class_linker_test

Bad Throwable field name in the test.

Change-Id: I48f5b3f9aaaa073443058a0c0a7db2327e8a1445
diff --git a/runtime/class_linker_test.cc b/runtime/class_linker_test.cc
index a1d5e53..5741de9 100644
--- a/runtime/class_linker_test.cc
+++ b/runtime/class_linker_test.cc
@@ -536,7 +536,7 @@
 
 struct ThrowableOffsets : public CheckOffsets<mirror::Throwable> {
   ThrowableOffsets() : CheckOffsets<mirror::Throwable>(false, "Ljava/lang/Throwable;") {
-    offsets.push_back(CheckOffset(OFFSETOF_MEMBER(mirror::Throwable, backtrace_),           "backtrace_"));
+    offsets.push_back(CheckOffset(OFFSETOF_MEMBER(mirror::Throwable, backtrace_),           "backtrace"));
     offsets.push_back(CheckOffset(OFFSETOF_MEMBER(mirror::Throwable, cause_),                 "cause"));
     offsets.push_back(CheckOffset(OFFSETOF_MEMBER(mirror::Throwable, detail_message_),        "detailMessage"));
     offsets.push_back(CheckOffset(OFFSETOF_MEMBER(mirror::Throwable, stack_trace_),           "stackTrace"));