It appears that tone() and noTone() were left out in the port of Energia to MSP432.
C:\Users\schen\AppData\Local\Temp\build4827627254845353855.tmp/W18_PWM_buzzer.ino:16: undefined reference to `tone(unsigned char, unsigned int)'
C:\Users\schen\AppData\Local\Temp\build4827627254845353855.tmp/W18_PWM_buzzer.ino:19: undefined reference to `noTone(unsigned char)'
collect2.exe: error: ld returned 1 exit status