On Cloud9, upgrade PHP 5 to 7.

up-to-php7-in-cloud9.sh

# Install phpbrew
sudo apt-get update
sudo apt-get install libmcrypt-dev
curl -L -O https://github.com/phpbrew/phpbrew/raw/master/phpbrew
chmod +x phpbrew
sudo mv phpbrew /usr/local/bin/
phpbrew init

[[ -e ~/.phpbrew/bashrc ]] && source ~/.phpbrew/bashrc

# Install php7
phpbrew lookup-prefix ubuntu
phpbrew install 7.0 +default
phpbrew switch php-7.0.1
phpbrew use php-7.0.1

# Install php7 module for apache
sudo add-apt-repository ppa:ondrej/php -y
sudo apt-get update -y

sudo apt-get install php7.0-curl php7.0-dev php7.0-gd php7.0-intl php7.0-mcrypt php7.0-json php7.0-mysql php7.0-opcache php7.0-bcmath php7.0-mbstring php7.0-soap php7.0-xml -y

sudo apt-get install libapache2-mod-php7.0 -y

# Switch apache module
sudo a2dismod php5
sudo a2enmod php7.0

Hey there! I've had the problem referenced in this issue for installing 7.1 and found that the solutions provided therein was helpful.

Specifically, running the following cURL install in the command line seemed to address that cURL error:

sudo apt-get install libcurl4-gnutls-dev

I don't have further insights into the issue, but it does seem, from reading, that it may be a bug within PHP's own build scripts, potentially.