libchewing: Negative-size-param in _Inner_InternalSpecialSymbol

Detailed report: https://clusterfuzz-external.appspot.com/testcase?key=5836280051007488 Fuzzer: libFuzzerlibchewingchewingdynamicconfigfuzzer Job Type: libfuzzerasanlibchewing Platform Id: linux Crash Type: Negative-size-param Crash Address: Crash State: InnerInternalSpecialSymbol EasySymbolInput...