Re-organise Makefile header dependencies

Add str.h to list of Serval header files.  Make the NaCl objects not dependent
on Serval header files, so that the entire NaCl source does not get re-built
when editing serval.h or str.h etc.

Makefile.in

@@ -2,14 +2,21 @@ NACL_BASE=	nacl/src
 include $(NACL_BASE)/nacl.mk
 SERVAL_BASE=
 include sourcefiles.mk
-SRCS=	$(NACL_SOURCES) $(SERVAL_SOURCES)
 include headerfiles.mk
 
 HAVE_ALSA= @HAVE_ALSA@
 ifeq (HAVE_ALSA,1)
-SRCS+=	audio_alsa.c
+SERVAL_SOURCES+=	$(SERVAL_BASE)/audio_alsa.c
 endif
 
+HAVE_VOIPTEST=	@HAVE_VOIPTEST@
+ifeq ($(HAVE_VOIPTEST), 1)
+SERVAL_SOURCES+=	$(SERVAL_BASE)/pa_phone.c
+VOIPTEST_CFLAGS=-DHAVE_VOIPTEST=1
+endif
+
+SRCS=	$(NACL_SOURCES) $(SERVAL_SOURCES)
+
 MONITORCLIENTSRCS=conf.c \
 	log.c \
 	mkdir.c \
@@ -29,14 +36,8 @@ MDPCLIENTSRCS=conf.c \
 	strbuf.c \
 	strbuf_helpers.c
 
-HAVE_VOIPTEST=	@HAVE_VOIPTEST@
-ifeq ($(HAVE_VOIPTEST), 1)
-SRCS+=	pa_phone.c
-VOIPTEST_CFLAGS=-DHAVE_VOIPTEST=1
-endif
-
 OBJS=	$(SRCS:.c=.o)
-
+SERVAL_OBJS=	$(SERVAL_SOURCES:.c=.o)
 MONITORCLIENTOBJS=	$(MONITORCLIENTSRCS:.c=.o)
 MDPCLIENTOBJS=	$(MDPCLIENTSRCS:.c=.o)
 
@@ -60,10 +61,14 @@ sqlite-amalgamation-3070900/sqlite3.o:	sqlite-amalgamation-3070900/sqlite3.c
 	@echo CC $<
 	@$(CC) $(CFLAGS) $(DEFS) -c $< -o sqlite-amalgamation-3070900/sqlite3.o
 
-%.o:	%.c $(HDRS)
+%.o:	%.c
 	@echo CC $<
 	@$(CC) $(CFLAGS) $(DEFS) -c $< -o $@
 
+$(SERVAL_OBJS): $(HDRS)
+$(MONITORCLIENTOBJS): $(HDRS)
+$(MDPCLIENTOBJS): $(HDRS)
+
 servald:	$(OBJS)
 	@echo LINK $@
 	@$(CC) $(CFLAGS) -Wall -o $@ $(OBJS) $(LDFLAGS)

headerfiles.mk

@@ -5,6 +5,7 @@ HDRS=	fifo.h \
 	overlay_packet.h \
 	rhizome.h \
 	serval.h \
+	str.h \
 	strbuf.h \
 	strbuf_helpers.h \
 	sha2.h \