centos升级C++17

yum install centos-release-scl
yum-config-manager --enable rhel-server-rhscl-7-rpms
yum install devtoolset-7
scl enable devtoolset-7 bash
ln -s /opt/rh/devtoolset-7/root/bin/gcc /usr/bin/gcc
ln -s /opt/rh/devtoolset-7/root/bin/g++ /usr/bin/g++
ln -s /opt/rh/devtoolset-7/root/bin/c++ /usr/bin/c++