dri: Unset current context and dispatch table when unbinding

Otherwise, when we switch to an indirect glx context and then back, it looks
like we're still current.

https://bugs.freedesktop.org/show_bug.cgi?id=29977#c7
Signed-off-by: Kristian Høgsberg <krh@bitplanet.net>

src/mesa/drivers/dri/intel/intel_context.c

@@ -873,6 +873,9 @@ intelDestroyContext(__DRIcontext * driContextPriv)
 GLboolean
 intelUnbindContext(__DRIcontext * driContextPriv)
 {
+   /* Unset current context and dispath table */
+   _mesa_make_current(NULL, NULL, NULL);
+
    return GL_TRUE;
 }
 

src/mesa/drivers/dri/nouveau/nouveau_context.c

@@ -306,6 +306,9 @@ nouveau_context_make_current(__DRIcontext *dri_ctx, __DRIdrawable *dri_draw,
 GLboolean
 nouveau_context_unbind(__DRIcontext *dri_ctx)
 {
+	/* Unset current context and dispath table */
+	_mesa_make_current(NULL, NULL, NULL);
+
 	return GL_TRUE;
 }
 

src/mesa/drivers/dri/radeon/radeon_common_context.c

@@ -363,6 +363,9 @@ GLboolean radeonUnbindContext(__DRIcontext * driContextPriv)
 		fprintf(stderr, "%s ctx %p\n", __FUNCTION__,
 			radeon->glCtx);
 
+	/* Unset current context and dispath table */
+	_mesa_make_current(NULL, NULL, NULL);
+
 	return GL_TRUE;
 }
 

src/mesa/drivers/dri/swrast/swrast.c

@@ -713,6 +713,10 @@ dri_unbind_context(__DRIcontext * cPriv)
 {
     TRACE;
     (void) cPriv;
+
+    /* Unset current context and dispath table */
+    _mesa_make_current(NULL, NULL, NULL);
+
     return GL_TRUE;
 }