Skip CMake configure step when CMakeCache.txt is present in build folder

[gferon]

When configuring big projects, not re-running CMake every time improves
the cargo build user experience.

[alexcrichton]

Thanks! Could this perhaps be an option on Config? I've had bad luck historically with not rerunning cmake for incremental builds causing very weird issues. Having this as an option definitely makes sense though!

[gferon]

Agreed, the ways of CMake are (sometimes) impenetrable.

What would be a good name for such option?

[alexcrichton]

Maybe something like .cache_configure(true)?

[gferon]

Maybe .always_configure(false) where the default is true would be easier to understand?

Anyway, I'll implement it and add the relevant doc, then we can always change it.

[alexcrichton]

Sounds great!

[alexcrichton]

👍 Thanks!