Cannot include Clutter headers on Debian sid

[aalex]

It seems like the gl.pc pkg-config file is missing from the OpenGL development packages on Debian sid.

aalex@plank:~/src/toonloop$ pkg-config --cflags --libs clutter-1.0
Package gl was not found in the pkg-config search path.
Perhaps you should add the directory containing `gl.pc'
to the PKG_CONFIG_PATH environment variable
Package 'gl', required by 'Clutter', not found

See http://www.linuxquestions.org/questions/linux-software-2/gl-pc-missing-781924/