test(runtime-c-api) Transforms all C/C++ warnings into errors.

This patch ensures that all our examples and tests do not generate
warnings. In C, it can be catastrophic sometimes…

Also, be sure that the `cmake` command doesn't emit any warnings too.

lib/runtime-c-api/tests/runtime_c_api_tests.rs

@@ -3,37 +3,47 @@ use std::process::Command;
 #[test]
 fn test_c_api() {
     let project_tests_dir = concat!(env!("CARGO_MANIFEST_DIR"), "/tests");
+
     run_command("cmake", project_tests_dir, Some("."));
-    run_command("make", project_tests_dir, None);
+    run_command("make", project_tests_dir, Some("-Wdev -Werror=dev"));
     run_command("make", project_tests_dir, Some("test"));
 }
 
 fn run_command(command_str: &str, dir: &str, arg: Option<&str>) {
     println!("Running command: `{}` arg: {:?}", command_str, arg);
+
     let mut command = Command::new(command_str);
+
     if let Some(a) = arg {
         command.arg(a);
     }
+
     command.current_dir(dir);
+
     let result = command.output();
+
     match result {
         Ok(r) => {
             println!("output:");
+
             if let Some(code) = r.status.code() {
                 println!("status: {}", code);
             } else {
                 println!("status: None");
             }
+
             println!("stdout:");
             println!("{}", String::from_utf8_lossy(&r.stdout[..]));
             println!("stderr:");
             println!("{}", String::from_utf8_lossy(&r.stderr[..]));
+
             if r.status.success() {
                 assert!(true)
             } else {
                 panic!("Command failed with exit status: {:?}", r.status);
             }
         }
+
         Err(e) => panic!("Command failed: {}", e),
     }
 }