Run lmdb tests alongside `cargo test`

Signed-off-by: Victor Porof <victor.porof@gmail.com>

lmdb-sys/tests/lmdb.rs

@@ -0,0 +1,28 @@
+extern crate lmdb_rkv_sys;
+
+use std::env;
+use std::path::PathBuf;
+use std::process::Command;
+
+#[test]
+fn test_lmdb() {
+  let mut lmdb = PathBuf::from(&env::var("CARGO_MANIFEST_DIR").unwrap());
+  lmdb.push("lmdb");
+  lmdb.push("libraries");
+  lmdb.push("liblmdb");
+
+  let make_cmd = Command::new("make")
+    .current_dir(&lmdb)
+    .status()
+    .expect("failed to execute process");
+
+  assert_eq!(make_cmd.success(), true);
+
+  let make_test_cmd = Command::new("make")
+    .arg("test")
+    .current_dir(&lmdb)
+    .status()
+    .expect("failed to execute process");
+
+  assert_eq!(make_test_cmd.success(), true);
+}