Commit efa25e7d5b

Several enhancements to the build system. Many breaking changes to the API. * combine `std.build` and `std.build.Builder` into `std.Build` * eliminate `setTarget` and `setBuildMode`; use an options struct for `b.addExecutable` and friends * implement passing options to dependency packages. closes #14285 * rename `LibExeObjStep` to `CompileStep` * move src.type.CType to std lib, use it from std.Build, this helps with populating config.h files.