build: add android support

Adds configuration target for android which disable ARPA nameserver
resolution to resolve build errors.

gyp_uv was modified from uv and included in cares as gyp_cares to
allow the same build regimen as is available in libuv within libcares.

To build with android support, run:

    source ./android-configure NDK_PATH
    make

To build with android support using gyp, run:

    source ./android-configure NDK_PATH gyp
    make -C out
gitignore: ignore build/gyp