Hmm that does appear to be the case, that's unfortunate, but could this be a separate define?

Something like

```
ifeq ($(OSTYPE_$(1)), linux-androideabi)
LIBUV_OS_$(1) = -DOS=android
else
LIBUV_OS_$(1) =
endif
```

and then you use `LIBUV_OS_$(1)` in the same rule.