Add NATIVE_WINDOWS

With a change of libs, and specifying NATIVE_WINDOWS as TARGET_OS it should compile libleveldb.a and libmemenv.a just fine, it did for me and Diapolo when testing.

src/leveldb/build_detect_platform

@@ -119,6 +119,16 @@ case "$TARGET_OS" in
         PLATFORM_EXTRALIBS="-lboost_system-mt-s -lboost_filesystem-mt-s -lboost_thread_win32-mt-s"
         CROSS_COMPILE=true
         ;;
+  NATIVE_WINDOWS)
+        PLATFORM=OS_WINDOWS
+        COMMON_FLAGS="-fno-builtin-memcmp -D_REENTRANT -DOS_WINDOWS -DLEVELDB_PLATFORM_WINDOWS -DBOOST_THREAD_USE_LIB"
+        PLATFORM_CXXFLAGS=""
+        PLATFORM_LDFLAGS=""
+        PLATFORM_SHARED_CFLAGS=""
+        PLATFORM_SOURCES="port/port_win.cc util/env_boost.cc util/win_logger.cc"
+		PLATFORM_EXTRALIBS="-lboost_system-mgw45-mt-s-1_50 -lboost_filesystem-mgw45-mt-s-1_50 -lboost_thread-mgw45-mt-s-1_50 -lboost_chrono-mgw45-mt-s-1_50"
+        CROSS_COMPILE=true	
+	    ;;
     *)
         echo "Unknown platform!" >&2
         exit 1