brew doctor

gistfile1.txt

You have a non-brew 'pkg-config' in your PATH:
  /usr/bin/pkg-config

`./configure` may have problems finding brew-installed packages using
this other pkg-config.

Your pkg-config is not checking "/usr/X11/lib/pkgconfig" for packages.
Earlier versions of the pkg-config formula did not add this path
to the search path, which means that other formula may not be able
to find certain dependencies.

To resolve this issue, re-brew pkg-config with:
  brew rm pkg-config && brew install pkg-config

Some "config" scripts were found in your path, but not in system or Homebrew folders.

`./configure` scripts often look for *-config scripts to determine if software packages
are installed, and what additional flags to use when compiling and linking.

Having additional scripts in your path can confuse software installed via Homebrew if
the config script overrides a system or Homebrew provided script of the same name.

/Library/Frameworks/Python.framework/Versions/Current/bin
    python-config python2.5-config
/Library/Frameworks/Python.framework/Versions/2.6/bin
    python-config python2.6-config

/Library/Frameworks/Mono.framework detected

This can be picked up by Cmake's build system and likey cause the
build to fail, finding improper header files for libpng for instance.