Build minijail as rust crate

minijail isn't packaged for normal Linux systems. Package it as a crate so it
can be built into the crosvm binary when minijail isn't available via
pkg-config.

BUG=chromium:1032360
TEST=cargo build

Change-Id: I7939d02399b28fe55fcd53fddec246e6129b4181
diff --git a/Cargo.toml b/Cargo.toml
new file mode 100644
index 0000000..6954d53
--- /dev/null
+++ b/Cargo.toml
@@ -0,0 +1,16 @@
+[package]
+name = "minijail-sys"
+version = "0.0.11"
+authors = ["The Chromium OS Authors"]
+edition = "2018"
+build = "build.rs"
+
+[lib]
+path = "lib.rs"
+
+[dependencies]
+libc = "0.2.44"
+
+[build-dependencies]
+cc = "1.0"
+pkg-config = "0.3"