I'm trying to install captcha npm module, which exploits the canvas module.

Unfortunately I have problem to install that module on OSX. 
I'm getting the following error:

```
> canvas@1.0.4 install ....../node_modules/canvas
> node-gyp rebuild

not found: ldconfig
gyp: Call to './util/has_lib.sh jpeg' returned exit status 0. while trying to load binding.gyp
gyp ERR! configure error 
gyp ERR! stack Error: `gyp` failed with exit code: 1
gyp ERR! stack     at ChildProcess.onCpExit (/usr/local/Cellar/node/0.10.21/lib/node_modules/npm/node_modules/node-gyp/lib/configure.js:424:16)
gyp ERR! stack     at ChildProcess.EventEmitter.emit (events.js:98:17)
gyp ERR! stack     at Process.ChildProcess._handle.onexit (child_process.js:789:12)
gyp ERR! System Darwin 13.0.0
gyp ERR! command "node" "/usr/local/Cellar/node/0.10.21/lib/node_modules/npm/node_modules/node-gyp/bin/node-gyp.js" "rebuild"
gyp ERR! cwd ...../node_modules/canvas
gyp ERR! node -v v0.10.21
gyp ERR! node-gyp -v v0.10.10
gyp ERR! not ok 
npm ERR! weird error 1

```

Any idea? Apparently there is ldconfig missing. But no idea how to install it.

I'm using homebrew, and I have the lastest XCode, and command line tools installed.