libchewing: Heap-buffer-overflow in CallPhrasing

Detailed report: https://clusterfuzz-external.appspot.com/testcase?key=5186601554542592 Fuzzer: libFuzzerlibchewingchewingdynamicconfigfuzzer Job Type: libfuzzerasanlibchewing Platform Id: linux Crash Type: Heap-buffer-overflow READ 4 Crash Address: 0x7f955b667fb0 Crash State: CallPhrasing...