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/elf_writer_quick.cc b/compiler/elf_writer_quick.cc
index 864e1b1..e5dfe68 100644
--- a/compiler/elf_writer_quick.cc
+++ b/compiler/elf_writer_quick.cc
@@ -23,12 +23,12 @@
 #include "base/logging.h"
 #include "base/stl_util.h"
 #include "compiled_method.h"
+#include "debug/elf_writer_debug.h"
+#include "debug/method_debug_info.h"
 #include "driver/compiler_options.h"
-#include "dwarf/method_debug_info.h"
 #include "elf.h"
 #include "elf_builder.h"
 #include "elf_utils.h"
-#include "elf_writer_debug.h"
 #include "globals.h"
 #include "leb128.h"
 #include "linker/buffered_output_stream.h"