message: Android.rules: fix building on windows
  $(realpath), which I guess is a make builtin, gives strange results on
  Windows. $(shell realpath) invokes the gnuwin external binary, which
  works correctly.
diff: NDK_ROOT := $(shell dirname $(CC))/../../../../..
  -NDK_ROOT := $(realpath $(NDK_ROOT))
  +NDK_ROOT := $(shell realpath $(NDK_ROOT))
  ifeq "$(findstring 64, $(ARCH))" "64"
  # lowest 64-bit API level
  