--output-dir fails if any cdylib exists in the workspace without a .so file

[notdanilo]

These lines makes it fail if we have another cdylib crate without a .so file.

https://github.com/bbqsrc/cargo-ndk/blob/87b29eee5c5be6e7e6f5e002e857df0885d6b470/src/cli/mod.rs#L743-L753

It adds two problems:

1. cargo ndk fails if the host is windows & another cdylib crate exists compiled to .dll
2. cargo ndk will incorrectly copy .so files if host is linux & another cdylib crate exists with .so compiled to a non-android platform

I could fix this, but I don't know what would be the ideal way to do it without adding a breaking change.