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/console.c

@@ -0,0 +1,59 @@
+/*
+ * FreeRTOS Kernel V10.3.0
+ * Copyright (C) 2020 Cambridge Consultants Ltd.
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy of
+ * this software and associated documentation files (the "Software"), to deal in
+ * the Software without restriction, including without limitation the rights to
+ * use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of
+ * the Software, and to permit persons to whom the Software is furnished to do so,
+ * subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in all
+ * copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS
+ * FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR
+ * COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER
+ * IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
+ * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
+ *
+ * http://www.FreeRTOS.org
+ * http://aws.amazon.com/freertos
+ *
+ * 1 tab == 4 spaces!
+ */
+
+/*-----------------------------------------------------------
+ * Example console I/O wrappers.
+ *----------------------------------------------------------*/
+
+#include <stdarg.h>
+#include <stdio.h>
+
+#include <FreeRTOS.h>
+#include <semphr.h>
+
+SemaphoreHandle_t xStdioMutex;
+StaticSemaphore_t xStdioMutexBuffer;
+
+void console_init(void)
+{
+    xStdioMutex = xSemaphoreCreateMutexStatic(&xStdioMutexBuffer);
+}
+
+void console_print(const char *fmt, ...)
+{
+    va_list vargs;
+
+    va_start(vargs, fmt);
+    
+    xSemaphoreTake(xStdioMutex, portMAX_DELAY);
+
+    vprintf(fmt, vargs);
+
+    xSemaphoreGive(xStdioMutex);
+
+    va_end(vargs);
+}