Couldn't find package opengl

Hi all,
I am trying to build xorg xserver and I am getting the following error from a script in the install:
No package ‘gl’ found

Consider adjusting the PKG_CONFIG_PATH environment variable if you
installed software in a non-standard prefix.

Alternatively, you may set the environment variables GL_CFLAGS
and GL_LIBS to avoid the need to call pkg-config.
See the pkg-config man page for more details.
Im using Ubuntu Linux 8.04.
I cant seem to find out what package I need to install to avoid this error.

With same ubuntu version, I see libgl1-mesa-dev installed, try this one.