Fix Posix demo build and remove src directory (#213)

* Fix: build errors, remove src directory and bring all files up
* Fix: Remove not needed header
* Doc: fix main comments
* Doc: fix comment

Co-authored-by: Alfred Gedeon <gedeonag@amazon.com>

FreeRTOS/Demo/Posix_GCC/utils/wait_for_event.c

@@ -0,0 +1,75 @@
+#include <pthread.h>
+#include <stdlib.h>
+#include <errno.h>
+
+#include "wait_for_event.h"
+
+struct event
+{
+    pthread_mutex_t mutex;
+    pthread_cond_t cond;
+    bool event_triggered;
+};
+
+struct event * event_create()
+{
+    struct event * ev = malloc( sizeof( struct event ) );
+
+    ev->event_triggered = false;
+    pthread_mutex_init( &ev->mutex, NULL );
+    pthread_cond_init( &ev->cond, NULL );
+    return ev;
+}
+
+void event_delete( struct event * ev )
+{
+    pthread_mutex_destroy( &ev->mutex );
+    pthread_cond_destroy( &ev->cond );
+    free( ev );
+}
+
+bool event_wait( struct event * ev )
+{
+    pthread_mutex_lock( &ev->mutex );
+
+    while( ev->event_triggered == false )
+    {
+        pthread_cond_wait( &ev->cond, &ev->mutex );
+    }
+
+    pthread_mutex_unlock( &ev->mutex );
+    return true;
+}
+bool event_wait_timed( struct event * ev,
+                       time_t ms )
+{
+    struct timespec ts;
+    int ret = 0;
+
+    clock_gettime( CLOCK_REALTIME, &ts );
+    //ts.tv_sec += ms;
+    ts.tv_nsec += (ms * 1000000);
+    pthread_mutex_lock( &ev->mutex );
+
+    while( (ev->event_triggered == false) && (ret == 0) )
+    {
+        ret = pthread_cond_timedwait( &ev->cond, &ev->mutex, &ts );
+
+        if( ( ret == -1 ) && ( errno == ETIMEDOUT ) )
+        {
+            return false;
+        }
+    }
+
+    ev->event_triggered = false;
+    pthread_mutex_unlock( &ev->mutex );
+    return true;
+}
+
+void event_signal( struct event * ev )
+{
+    pthread_mutex_lock( &ev->mutex );
+    ev->event_triggered = true;
+    pthread_cond_signal( &ev->cond );
+    pthread_mutex_unlock( &ev->mutex );
+}