vfs and newlib: small fixes

- spaces->tabs in tasks.c
- update vfs_uart.c to use per-UART locks
- add license to vfs_uart.c
- allocate separate streams for stdout, stdin, stderr, so that they can be independently reassigned
- fix build system test failure

components/esp32/include/soc/cpu.h

@@ -15,6 +15,9 @@
 #ifndef _SOC_CPU_H
 #define _SOC_CPU_H
 
+#include <stdint.h>
+#include <stdbool.h>
+#include <stddef.h>
 #include "xtensa/corebits.h"
 
 /* C macros for xtensa special register read/write/exchange */