GLEW resolves its entry points through GLX unless built with GLEW_EGL. On a
display stack that provides no GLX -- Wayland, or GBM -- glxewInit() returns
GLEW_ERROR_NO_GLX_DISPLAY, glewInit() fails, and the GL backend never starts.
Building the EGL backend resolves them through eglGetProcAddress instead, which
works on both. It is opt-in rather than the default so existing GLX builds are
untouched.
Note that changing this needs ext/glew/glew.o deleted to take effect, since the
Makefile is not a prerequisite of the object.
Chris
3a77d51df1