Initial reorg.

This is largely the same as #305, but updated for the current tree.

crates/runtime/build.rs

@@ -0,0 +1,20 @@
+fn main() {
+    println!("cargo:rerun-if-changed=signalhandlers/SignalHandlers.cpp");
+    println!("cargo:rerun-if-changed=signalhandlers/SignalHandlers.hpp");
+    println!("cargo:rerun-if-changed=signalhandlers/Trampolines.cpp");
+    let target = std::env::var("TARGET").unwrap();
+    let mut build = cc::Build::new();
+    build
+        .cpp(true)
+        .warnings(false)
+        .file("signalhandlers/SignalHandlers.cpp")
+        .file("signalhandlers/Trampolines.cpp");
+    if !target.contains("windows") {
+        build
+            .flag("-std=c++11")
+            .flag("-fno-exceptions")
+            .flag("-fno-rtti");
+    }
+
+    build.compile("signalhandlers");
+}