Comment # 4 on bug 93970 from Ilia Mirkin

There's a drirc entry for Second Life already:

        <application name="Second Life"
executable="do-not-directly-run-secondlife-bin">
            <option name="allow_glsl_extension_directive_midshader"
value="true" />
        </application>

You could just add the other option there as well - no need to set them
globally (in fact, it might cause other things to break as a result - various
exts can cause older shaders to become invalid, as keywords are added/etc).