Error compiling for board MKR1000

Dear all,

I have been using MKR1000 for some years. Recently, it fails to compile codes even I run blank sketch. However, when I run the same code in UNO, it works. the error message is as follows:
```
In file included from C:\Users\Joe\AppData\Local\Arduino15\packages\arduino\hardware\samd\1.8.6\cores\arduino/Arduino.h:24:0,

from sketch\sketch_jun16a.ino.cpp:1:

c:\users\joe\appdata\local\arduino15\packages\arduino\tools\arm-none-eabi-gcc\7-2017q4\lib\gcc\arm-none-eabi\7.2.1\include\stdint.h:9:16: fatal error: stdint.h: No such file or directory

# include_next

^~~~~~~~~~

compilation terminated.

exit status 1
Error compiling for board Arduino MKR1000.
```
May I know what is wrong?

Reproduce the blank-sketch compilation failure for the Arduino MKR1000 and compare it with the working UNO build. Start with the reported Arduino.h include path and the arm-none-eabi-gcc 7.2.1 stdint.h error; done means identifying why the MKR1000 toolchain cannot locate stdint.h and confirming that a blank sketch compiles successfully.

Written by the indexing model from the issue text.