Set ninja=true by default

Ninja substantially improves LLVM build time. On a 96-way system, using
Make took 248s, and using Ninja took 161s, a 35% improvement.

We already require a variety of tools to build Rust. If someone wants to
build without Ninja (for instance, to minimize the set of packages
required to bootstrap a new target), they can easily set `ninja=false`
in `config.toml`.  Our defaults should help people build Rust (and LLVM)
faster, to speed up development.

1 files changed, 1 insertions, 0 deletions

diff --git a/src/bootstrap/config.rs b/src/bootstrap/config.rs
index 8b8b01b1153..f549de6570f 100644
--- a/src/bootstrap/config.rs
+++ b/src/bootstrap/config.rs
@@ -450,6 +450,7 @@ impl Config {
     pub fn default_opts() -> Config {
         let mut config = Config::default();
         config.llvm_optimize = true;
+        config.ninja = true;
         config.llvm_version_check = true;
         config.backtrace = true;
         config.rust_optimize = true;