glx: Simplify some dummy vtable interactions

The dummy vtable has these slots as NULL already, no need to check for
the dummy context explicitly.

Signed-off-by: Adam Jackson <ajax@redhat.com>
Reviewed-by: Emil Velikov <emil.velikov@collabora.com>
diff --git a/src/glx/glxcmds.c b/src/glx/glxcmds.c
index c707d0c..bc93d62 100644
--- a/src/glx/glxcmds.c
+++ b/src/glx/glxcmds.c
@@ -528,7 +528,7 @@
 {
    struct glx_context *gc = __glXGetCurrentContext();
 
-   if (gc != &dummyContext && gc->vtable->wait_gl)
+   if (gc->vtable->wait_gl)
       gc->vtable->wait_gl(gc);
 }
 
@@ -541,7 +541,7 @@
 {
    struct glx_context *gc = __glXGetCurrentContext();
 
-   if (gc != &dummyContext && gc->vtable->wait_x)
+   if (gc->vtable->wait_x)
       gc->vtable->wait_x(gc);
 }
 
@@ -550,7 +550,7 @@
 {
    struct glx_context *gc = __glXGetCurrentContext();
 
-   if (gc != &dummyContext && gc->vtable->use_x_font)
+   if (gc->vtable->use_x_font)
       gc->vtable->use_x_font(gc, font, first, count, listBase);
 }
 
@@ -2431,7 +2431,7 @@
 {
    struct glx_context *gc = __glXGetCurrentContext();
 
-   if (gc == &dummyContext || gc->vtable->bind_tex_image == NULL)
+   if (gc->vtable->bind_tex_image == NULL)
       return;
 
    gc->vtable->bind_tex_image(dpy, drawable, buffer, attrib_list);
@@ -2442,7 +2442,7 @@
 {
    struct glx_context *gc = __glXGetCurrentContext();
 
-   if (gc == &dummyContext || gc->vtable->release_tex_image == NULL)
+   if (gc->vtable->release_tex_image == NULL)
       return;
 
    gc->vtable->release_tex_image(dpy, drawable, buffer);