Get a long list of compile warnings with the SdFat library in Seeeduino Xiao

[cgwaltney]

Looks like this is your problem…

C:\Users\xxxx.platformio\packages\framework-arduino-samd-seeed\variants\XIAO_m0/variant.h:219:25: warning: extra tokens at end of #endif directive [-Wendif-labels]
#endif SerialUSB
^~~~~~~~~