Debian's version of OpenGL is called Mesa and it supports normal
OpenGL on armel too, it would not be hardware-accelerated yet though
because there aren't any free drivers for that in Debian. Same goes
for hardware-acceleration of OpenGLES on ARM, no free drivers in
Debian yet. Some reverse engineering projects and free drivers exist
outside of Debian though:
https://wiki.debian.org/Mobile#software-drivers
You can install OpenGLES (libgles1-mesa-dev or libgles2-mesa-dev) on
your standard Debian amd64 PC system, try to build your code and
change it until it doesn't fail.
This will be hardware-accelerated and
be easier than messing around with cross-compilers.
Here are some guides for converting OpenGL code to OpenGLES, any
issues you encounter should be fixable by using a search engine
though.
http://pandorawiki.org/Porting_to_GLES_from_GL
http://software.intel.com/en-us/articles/porting-opengl-games-to-android-on-intel-atom-processors-part-1
http://wiki.maemo.org/OpenGL-ES