Move code related to debug info generation to its own directory.

debug/dwarf/ contains helper classes which hide the details
of the DWARF file format. It acts as independent DWARF library.

debug/ contains ART-specific code which generates ELF debug
sections (which includes non-DWARF sections like .symtab).

Change-Id: Id351f604e4e64be2ca395a78324ea02e30481497
diff --git a/compiler/image_test.cc b/compiler/image_test.cc
index a5a7796..4920f9b 100644
--- a/compiler/image_test.cc
+++ b/compiler/image_test.cc
@@ -23,7 +23,7 @@
 #include "base/unix_file/fd_file.h"
 #include "class_linker-inl.h"
 #include "common_compiler_test.h"
-#include "dwarf/method_debug_info.h"
+#include "debug/method_debug_info.h"
 #include "elf_writer.h"
 #include "elf_writer_quick.h"
 #include "gc/space/image_space.h"