Build raw sqlite interface as libsqlite3-sys

Use pkg-config to find it.

libsqlite3-sys/Cargo.toml

@@ -0,0 +1,11 @@
+[package]
+name = "libsqlite3-sys"
+version = "0.0.9"
+authors = ["John Gallagher <jgallagher@bignerdranch.com>"]
+description = "Native bindings to the libsqlite3 library"
+license = "MIT"
+links = "sqlite3"
+build = "build.rs"
+
+[build-dependencies]
+pkg-config = "~0.2"