call char_length on Chinese character will cause core dump.

>>set terminal_charset utf8;
>>select char_lentgh('中国人') from (values(1));
#
# A fatal error has been detected by the Java Runtime Environment:
#
#  SIGSEGV (0xb) at pc=0x00000000004024ea, pid=13636, tid=140591300516352
#
# JRE version: OpenJDK Runtime Environment (7.0_161) (build 1.7.0_161-mockbuild_2017_12_06_14_28-b00)
# Java VM: OpenJDK 64-Bit Server VM (24.161-b00 mixed mode linux-amd64 compressed oops)
# Derivative: IcedTea 2.6.12
# Distribution: CentOS release 6.9 (Final), package rhel-2.6.12.0.el6_9-x86_64 u161-b00
# Problematic frame:
# C  [sqlci+0x24ea]  folly::fbstring_core<char>::category() const+0xc
#
# Core dump written. Default location: /home/centos/incubator-trafodion/core or core.13636
#
# An error report file with more information is saved as:
# /tmp/jvm-13636/hs_error.log
#
# If you would like to submit a bug report, please include
# instructions on how to reproduce the bug and visit:
#   http://icedtea.classpath.org/bugzilla
# The crash happened outside the Java Virtual Machine in native code.
# See problematic frame for where to report the bug.
#
Aborted (core dumped)