Make --prominent-compile-errors the default

[silversquirl]

It's rare that I need to see the command that zig build failed on. I propose removing --prominent-compile-errors, which hides this command to make errors easier to read, and replacing it with the inverse: an option to show the failed command when an error occurs.

This new option could be named something like --verbose-failure, or this functionality could simply be removed, since it's kind of a subset of the normal --verbose option.