Fix the offset of $dexfile debug symbol.

The symbol is currently unused but will be needed soon.

It is also more convenient if it is marked as STT_FUNC.

Test: testrunner.py --intepreter -t 137 (with other CLs)
Change-Id: I47bcbb498c47cd662eb85aaeb0363678e54d6471
diff --git a/compiler/debug/elf_symtab_writer.h b/compiler/debug/elf_symtab_writer.h
index 9007360..a853714 100644
--- a/compiler/debug/elf_symtab_writer.h
+++ b/compiler/debug/elf_symtab_writer.h
@@ -108,7 +108,7 @@
       uint64_t dex_address = dex->GetAddress() + it.first /* offset within the section */;
       const DexFile* dex_file = it.second;
       typename ElfTypes::Word dex_name = strtab->Write(kDexFileSymbolName);
-      symtab->Add(dex_name, dex, dex_address, dex_file->Size(), STB_LOCAL, STT_NOTYPE);
+      symtab->Add(dex_name, dex, dex_address, dex_file->Size(), STB_GLOBAL, STT_FUNC);
       if (mini_debug_info) {
         continue;  // Don't add interpreter method names to mini-debug-info for now.
       }