reorder Build struct's fields based on the order in config.toml.example

Author: Guanqun Lu

src/bootstrap/config.rs

@@ -200,23 +200,23 @@ struct Build {
     target: Vec<String>,
     cargo: Option<String>,
     rustc: Option<String>,
-    low_priority: Option<bool>,
-    compiler_docs: Option<bool>,
     docs: Option<bool>,
+    compiler_docs: Option<bool>,
     submodules: Option<bool>,
     fast_submodules: Option<bool>,
     gdb: Option<String>,
-    locked_deps: Option<bool>,
-    vendor: Option<bool>,
     nodejs: Option<String>,
     python: Option<String>,
+    locked_deps: Option<bool>,
+    vendor: Option<bool>,
     full_bootstrap: Option<bool>,
     extended: Option<bool>,
     tools: Option<HashSet<String>>,
     verbose: Option<usize>,
     sanitizers: Option<bool>,
     profiler: Option<bool>,
     cargo_native_static: Option<bool>,
+    low_priority: Option<bool>,
     configure_args: Option<Vec<String>>,
     local_rebuild: Option<bool>,
     print_step_timings: Option<bool>,