Problem to detect OpenGL during configure

Hello. I am facing the following issue when trying to configure sdl 1.2.15.

During the configure execution I noticed:

checking for OpenGL (GLX) support… no

I went to read the config.log and found this:

/usr/local/include/GL/glext.h:37:29: error: KHR/khrplatform.h: No such file or directory

However, looking at /usr/local/include/GL, there is a KHR directory there, and inside it, there is the khrplatform.h file. So why configure is not finding the the file inside KHR dir?