build: split the non-gui startup routines into a new file

This will allow each to have its own main(), meaning that we can build a common
base client and simply link in the correct startup object to create the
appropriate binary.

src/makefile.linux-mingw

@@ -71,6 +71,7 @@ OBJS= \
     obj/key.o \
     obj/db.o \
     obj/init.o \
+    obj/bitcoind.o \
     obj/keystore.o \
     obj/main.o \
     obj/net.o \
@@ -116,7 +117,7 @@ TESTOBJS := $(patsubst test/%.cpp,obj-test/%.o,$(wildcard test/*.cpp))
 obj-test/%.o: test/%.cpp $(HEADERS)
 	$(CXX) -c $(TESTDEFS) $(xCXXFLAGS) -o $@ $<
 
-test_bitcoin.exe: $(TESTOBJS) $(filter-out obj/init.o,$(OBJS:obj/%=obj/%))
+test_bitcoin.exe: $(TESTOBJS) $(filter-out obj/init.o obj/bitcoind.o,$(OBJS:obj/%=obj/%))
 	$(CXX) $(xCXXFLAGS) $(xLDFLAGS) -o $@ $(LIBPATHS) $^ -lboost_unit_test_framework-mt-s $(LIBS)