Change to 0/1 instead of OFF/ON

On newer CMake's, the following errors are reported:

```
CMake Warning (dev) at .... /vcpkg/installed/x64-osx/share/c-ares/c-ares-config.cmake:32 (if):
  if given arguments:

    "ON"

  An argument named "ON" appears in a conditional statement.  Policy CMP0012
  is not set: if() recognizes numbers and boolean constants.  Run "cmake
  --help-policy CMP0012" for policy details.  Use the cmake_policy command to
  set the policy and suppress this warning.
```

Which corresponds to the following configured code:

```
if(ON)
    set(c-ares_STATIC_LIBRARY c-ares::cares_static)
endif()
```

0 files changed, 0 insertions, 0 deletions