test: Add remaining three egl-opengl tests

In a previous commit message, I had suggested we would be adding five
additional tests here. But unlike GLX, EGL provides only
eglGetProcAddress, (and no eglGetProcAddressARB), so two of the GLX
variants don't apply.

The two dlopen-based tests are currently failing when run under fips,
so once again the test suite has come through and found another bug.