updated SIGINT handler - as per comments in mochajs#3570

Signed-off-by: jayasankar <jayasankar.m@gmail.com>

lib/cli/run-helpers.js

@@ -204,6 +204,7 @@ exports.singleRun = (mocha, {files = [], exit = false} = {}) => {
     // Instead of `process.exit(130)`, set runner.failures to 130 (exit code for SIGINT)
     // The amount of failures will be emitted as error code later
     runner.failures = 130;
+    setImmediate(() => process.kill(process.pid, 'SIGINT'));
   });
 };