Include CMmake configuration stdio

Summary: Include error messages or other output for CMake generating the build for ninja

Reviewed By: yungsters

Differential Revision: D46884396

fbshipit-source-id: a31ae4dbdecd8833e62d8e3b8bf8dcaae9ba67e2

javascript/just.config.ts

@@ -175,7 +175,7 @@ function emcmakeGenerateTask() {
     ];
     logger.info(['emcmake', ...args].join(' '));
 
-    return spawn(emcmake, args);
+    return spawn(emcmake, args, {stdio: 'inherit'});
   };
 }