Fix linux-mingw makefile's leveldb build by setting CXX.

src/makefile.linux-mingw

@@ -92,7 +92,7 @@ LIBS += $(CURDIR)/leveldb/libleveldb.a $(CURDIR)/leveldb/libmemenv.a
 DEFS += -I"$(CURDIR)/leveldb/include"
 DEFS += -I"$(CURDIR)/leveldb/helpers"
 leveldb/libleveldb.a:
-	@echo "Building LevelDB ..." && cd leveldb && TARGET_OS=OS_WINDOWS_CROSSCOMPILE CXXFLAGS="-I$(INCLUDEPATHS)" LDFLAGS="-L$(LIBPATHS)" make libleveldb.a libmemenv.a && cd ..
+	@echo "Building LevelDB ..." && cd leveldb && CXX=i586-mingw32msvc-g++ TARGET_OS=OS_WINDOWS_CROSSCOMPILE CXXFLAGS="-I$(INCLUDEPATHS)" LDFLAGS="-L$(LIBPATHS)" make libleveldb.a libmemenv.a && cd ..
 obj/leveldb.o: leveldb/libleveldb.a
 
 obj/build.h: FORCE