glx: Make #undef GLX_INDIRECT_RENDERING do something

Not that meson lets you reach this state yet, but if you did, you'd
still build all of the indirect code but the linker would gc most of it.

Reviewed-by: Alyssa Rosenzweig <alyssa@rosenzweig.io>
Reviewed-by: Eric Engestrom <eric@igalia.com>
Reviewed-by: Marek Olšák <marek.olsak@amd.com>
Acked-By: Mike Blumenkrantz <michael.blumenkrantz@gmail.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/33623>

src/glx/create_context.c

@@ -108,9 +108,11 @@ glXCreateContextAttribsARB(Display *dpy, GLXFBConfig config,
                       (const uint32_t *) attrib_list,
                       &error);
    } else if (!direct) {
+#ifdef GLX_INDIRECT_RENDERING
       gc = indirect_create_context_attribs(psc, cfg, share, num_attribs,
                                            (const uint32_t *) attrib_list,
                                            &error);
+#endif
    }
 #endif
 

src/glx/glxcmds.c

@@ -321,8 +321,10 @@ CreateContext(Display *dpy, int generic_id, struct glx_config *config,
 #else
    if (allowDirect && psc->vtable->create_context)
       gc = psc->vtable->create_context(psc, config, shareList, renderType);
+#ifdef GLX_INDIRECT_RENDERING
    if (!gc)
       gc = indirect_create_context(psc, config, shareList, renderType);
+#endif
 #endif
    if (!gc)
       return NULL;
@@ -1318,7 +1320,9 @@ glXImportContextEXT(Display *dpy, GLXContextID contextID)
    if (mode == NULL)
       return NULL;
 
+#ifdef GLX_INDIRECT_RENDERING
    ctx = indirect_create_context(psc, mode, NULL, renderType);
+#endif
    if (ctx == NULL)
       return NULL;
 

src/glx/glxext.c

@@ -916,7 +916,9 @@ AllocAndFetchScreenConfigs(Display * dpy, struct glx_display * priv, enum glx_dr
 #else
       if (psc == NULL && !zink)
       {
+#ifdef GLX_INDIRECT_RENDERING
          psc = indirect_create_screen(i, priv);
+#endif
          indirect = true;
       }
 #endif