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/utils/assembler.h b/compiler/utils/assembler.h
index 1dbc142..414ea7e 100644
--- a/compiler/utils/assembler.h
+++ b/compiler/utils/assembler.h
@@ -21,9 +21,10 @@
 
 #include "arch/instruction_set.h"
 #include "arch/instruction_set_features.h"
+#include "arm/constants_arm.h"
 #include "base/logging.h"
 #include "base/macros.h"
-#include "arm/constants_arm.h"
+#include "debug/dwarf/debug_frame_opcode_writer.h"
 #include "label.h"
 #include "managed_register.h"
 #include "memory_region.h"
@@ -31,7 +32,6 @@
 #include "offsets.h"
 #include "x86/constants_x86.h"
 #include "x86_64/constants_x86_64.h"
-#include "dwarf/debug_frame_opcode_writer.h"
 
 namespace art {