Force -Os for upb_def.o

Makefile

@@ -48,11 +48,17 @@ clean:
 # The core library (src/libupb.a)
 SRC=src/upb.c src/upb_parse.c src/upb_table.c src/upb_def.c src/upb_data.c \
     descriptor/descriptor.c
-    #src/upb_serialize.c descriptor/descriptor.c
+# Override the optimization level for upb_def.o, because it is not in the
+# critical path but gets very large when -O3 is used.
+src/upb_def.o: src/upb_def.c
+	$(CC) $(CFLAGS) $(CPPFLAGS) -Os -c -o $@ $<
+src/upb_def.lo: src/upb_def.c
+	$(CC) $(CFLAGS) $(CPPFLAGS) -Os -c -o $@ $< -fPIC
+
 STATICOBJ=$(patsubst %.c,%.o,$(SRC))
 SHAREDOBJ=$(patsubst %.c,%.lo,$(SRC))
 # building shared objects is like building static ones, except -fPIC is added.
-%.lo : %.c ; $(CC) -fPIC $(CPPFLAGS) $(CFLAGS) -c -o $@ $<
+%.lo : %.c ; $(CC) $(CFLAGS) $(CPPFLAGS) -c -o $@ $< -fPIC
 $(LIBUPB): $(STATICOBJ)
 	ar rcs $(LIBUPB) $(STATICOBJ)
 $(LIBUPB_PIC): $(SHAREDOBJ)