Add audio/ sub-syste, include/nuttx/audio.h interface, and drivers/audio/vs1053.c driver to NuttX. From Ken Pettit

Makefile.win

@@ -133,6 +133,12 @@ else
 OTHERDIRS += graphics
 endif
 
+ifeq ($(CONFIG_AUDIO),y)
+NONFSDIRS += audio
+else
+OTHERDIRS += audio
+endif
+
 # CLEANDIRS are the directories that will clean in.  These are
 #   all directories that we know about.
 # KERNDEPDIRS are the directories in which we will build target dependencies.
@@ -245,6 +251,12 @@ ifeq ($(CONFIG_NX),y)
 NUTTXLIBS += lib\libgraphics$(LIBEXT)
 endif
 
+# Add libraries for the Audio sub-system
+
+ifeq ($(CONFIG_AUDIO),y)
+NUTTXLIBS += lib\libaudio$(LIBEXT)
+endif
+
 # LINKLIBS derives from NUTTXLIBS and is simply the same list with the subdirectory removed
 
 LINKLIBS = $(patsubst lib\\%,%,$(NUTTXLIBS))
@@ -524,6 +536,12 @@ graphics\libgraphics$(LIBEXT): context
 lib\libgraphics$(LIBEXT): graphics\libgraphics$(LIBEXT)
 	$(Q) install graphics\libgraphics$(LIBEXT) lib\libgraphics$(LIBEXT)
 
+audio\libaudio$(LIBEXT): context
+	$(Q) $(MAKE) -C audio TOPDIR="$(TOPDIR)" libaudio$(LIBEXT) EXTRADEFINES=$(KDEFINE)
+
+lib\libaudio$(LIBEXT): audio\libaudio$(LIBEXT)
+	$(Q) install audio\libaudio$(LIBEXT) lib\libaudio$(LIBEXT)
+
 syscall\libstubs$(LIBEXT): context
 	$(Q) $(MAKE) -C syscall TOPDIR="$(TOPDIR)" libstubs$(LIBEXT) EXTRADEFINES=$(KDEFINE)