The latest version of Phalcon uses PCRE libraries.
You can install them like so:
sudo apt-get install libpcre3-dev
and then try and install Phalcon again
For CentOS you will need to use
sudo yum install pcre-devel
Credits: @xgretsch
For Mac you can use
brew install pcre
Credits @Brandon Romano
For Mac without brew
Go to https://www.pcre.org/ and download latest pcre:,
tar -xzvf pcre-8.42.tar.gz
cd pcre-8.42
./configure --prefix=/usr/local/pcre-8.42
make
make install
ln -s /usr/local/pcre-8.42 /usr/sbin/pcre
ln -s /usr/local/pcre-8.42/include/pcre.h /usr/include/pcre.h
Credits @user1377324