Factor into a -sys crate and build libui ourselves

Author: pcwalton

.gitmodules

@@ -0,0 +1,3 @@
+[submodule "ui-sys/libui"]
+	path = ui-sys/libui
+	url = https://github.com/andlabs/libui

ui/LICENSE-APACHE renamed to LICENSE-APACHE

@@ -0,0 +1,14 @@
+[package]
+name = "ui-sys"
+version = "0.1.0"
+authors = ["Patrick Walton <[email protected]>"]
+build = "build.rs"
+license = "MIT/Apache 2.0"
+description = "Native bindings to the minimalist, cross-platform, widget set `libui`"
+
+[dependencies]
+libc = "0.2"
+
+[build-dependencies]
+make-cmd = "0.1"
+

ui/LICENSE-MIT renamed to LICENSE-MIT

@@ -0,0 +1,22 @@
+extern crate make_cmd;
+
+use std::env;
+use std::path::Path;
+use std::process::Command;
+
+fn main() {
+    if !Path::new("libui/.git").exists() {
+        Command::new("git").args(&["submodule", "update", "--init"]).status().unwrap();
+    }
+
+    let out_dir = env::var("OUT_DIR").unwrap();
+    let outdir_argument = format!("OUTDIR={}", out_dir);
+    let objdir_argument = format!("OBJDIR={}/obj", out_dir);
+    make_cmd::gnu_make().args(&["-C", "libui", &*outdir_argument, &*objdir_argument])
+                        .status()
+                        .unwrap();
+
+    println!("cargo:rustc-link-lib=dylib=ui");
+    println!("cargo:rustc-link-search=native={}", out_dir);
+}
+