yea, you have to update those I use ubuntu so i have to idea how does it work on CentOS.
in ubuntu its
cd /etc/alternatives;
ll | grep "php"
inside you should be able to see your shortcuts.
but before you edit them.
try editing your ~./.bashrc file
php=my path to php7/bin/php
phpize=my path to php7/bin/phpize
php-config=my path to php7/bin/php-config
try again which to make sure its there. Also php -v should say 7.0.10 .. or whatever it was.
they try installing again.
you can remove those configs in your bashrs after that.
The idea is that php extensions needs to be directed to the php-config file and they use it while compiling.