fork the esp-idf fatfs for f_forward and exfat support

lib/fatfs/port/linux/ffsystem.c

@@ -0,0 +1,45 @@
+/*------------------------------------------------------------------------*/
+/* OS Dependent Functions for FatFs                                       */
+/* (C)ChaN, 2018                                                          */
+/*------------------------------------------------------------------------*/
+
+
+#include "ff.h"
+#include <stdlib.h>
+
+/* This is the implementation for host-side testing on Linux.
+ * Host-side tests are single threaded, so lock functionality isn't needed.
+ */
+
+void* ff_memalloc(UINT msize)
+{
+    return malloc(msize);
+}
+
+void ff_memfree(void* mblock)
+{
+    free(mblock);
+}
+
+static int* Mutex[FF_VOLUMES + 1]; /* Table of mutex handle */
+
+/* 1:Function succeeded, 0:Could not create the mutex */
+int ff_mutex_create(int vol)
+{
+    Mutex[vol] = NULL;
+    return 1;
+}
+
+void ff_mutex_delete(int vol)
+{
+}
+
+/* 1:Function succeeded, 0:Could not acquire lock */
+int ff_mutex_take(int vol)
+{
+    return 1;
+}
+
+void ff_mutex_give(int vol)
+{
+}