build: exit on unsupported host OS for Android

[VoltrexKeyva]

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The Android configure script throws an unhelpful error message telling the user that toolchain_path is not defined when the script is run on an unsupported host OS, exit with a more helpful message instead while listing the supported host OSes.

[lpinca]

Wouldn't it be better to fix it here https://github.com/nodejs/node/blob/cbd6ddbb4a40b8d604ed7a1990f7133ae518fd41/android_configure.py#L13-L15

[VoltrexKeyva]

I assume this doesn't need a Jenkins CI right?

[nodejs-github-bot]

Landed in 0cbbab9a4d6a11c1fc219acfad54f05f51fec17b