Build Scripts should check command exit code in addition to invocation success

[vringar]

Describe the bug

As far as I could tell from a quick search most Command invocations in build.rs files only use a single unwrap on the result of the status(). However, the first unwrap only covers a failure to invoke the command, not whether it completed successfully. Mara Bos has confirmed this in this comment.

To Reproduce Steps to reproduce the behavior:

1. Don't install a required dependency to build qemu
2. Run cargo build --no-default-features -p libafl_qemu
3. Observe that the first error reported by the build script is Failed to read linkinfo.json as that is the "observable" error condition from the perspective of the build script.

Expected behavior

I would expect the error to be accurately attributed to the failing command.

Additional context

There are a couple of different ways this is handled in other buildscripts

https://github.com/AFLplusplus/LibAFL/blob/374f8735fa96c13ca2f74d0ead7fb40615504bed/libafl_libfuzzer/build.rs#L79-L82

https://github.com/AFLplusplus/LibAFL/blob/374f8735fa96c13ca2f74d0ead7fb40615504bed/libafl_nyx/build.rs#L10-L14

But there are also a lot of unhandled cases elsewhere like https://github.com/AFLplusplus/LibAFL/blob/374f8735fa96c13ca2f74d0ead7fb40615504bed/fuzzers/backtrace_baby_fuzzers/forkserver_executor/build.rs#L26-L30

https://github.com/AFLplusplus/LibAFL/blob/374f8735fa96c13ca2f74d0ead7fb40615504bed/libafl_frida/build.rs#L31-L33