On http://api.mongodb.org/c/current/installing.html, the text

Minimal dependencies are needed to build the MongoDB C driver. Optionally, if you want Kerberos (GSSAPI) or SSL support, you need to install libsasl2 and OpenSSL libraries and development headers respectively.

glances over the need for dev headers. Perhaps a bold on "and development headers" would be helpful.

For RedHat, CentOS, Fedora, related distros, mention "sudo yum install openssl-devel cyrus-sasl-devel", and the equivalent for Debian and derivatives. Windows and Mac users need even more explicit instructions to build from source – e.g., where to download CMake or how to install the Autotools on Mac with Homebrew – as well as instructions for building with SSL and SASL support.