[mutter] cogl: Remove deprecated backface_culing API

[Marge Bot <marge-bot src gnome org>]

commit b8925ef3d493ca3186b877e525cb8920c5f3aaca
Author: Fernando Monteiro <fr02monteiro gmail com>
Date:   Thu Sep 16 22:26:27 2021 +0100

    cogl: Remove deprecated backface_culing API
    
    They are unused.
    
    Part-of: <https://gitlab.gnome.org/GNOME/mutter/-/merge_requests/2058>

 cogl/cogl/cogl-context-private.h |  2 --
 cogl/cogl/cogl-context.c         |  2 --
 cogl/cogl/cogl.c                 | 19 -------------------
 cogl/cogl/cogl1-context.h        | 30 ------------------------------
 4 files changed, 53 deletions(-)
---
diff --git a/cogl/cogl/cogl-context-private.h b/cogl/cogl/cogl-context-private.h
index 4702fb4d09..e3a463bf25 100644
--- a/cogl/cogl/cogl-context-private.h
+++ b/cogl/cogl/cogl-context-private.h
@@ -114,8 +114,6 @@ struct _CoglContext
   CoglBitmask       enable_custom_attributes_tmp;
   CoglBitmask       changed_bits_tmp;
 
-  gboolean          legacy_backface_culling_enabled;
-
   /* A few handy matrix constants */
   graphene_matrix_t identity_matrix;
   graphene_matrix_t y_flip_matrix;
diff --git a/cogl/cogl/cogl-context.c b/cogl/cogl/cogl-context.c
index 26c12e9f8f..67bea6b8d2 100644
--- a/cogl/cogl/cogl-context.c
+++ b/cogl/cogl/cogl-context.c
@@ -224,8 +224,6 @@ cogl_context_new (CoglDisplay *display,
   context->current_clip_stack_valid = FALSE;
   context->current_clip_stack = NULL;
 
-  context->legacy_backface_culling_enabled = FALSE;
-
   graphene_matrix_init_identity (&context->identity_matrix);
   graphene_matrix_init_identity (&context->y_flip_matrix);
   graphene_matrix_scale (&context->y_flip_matrix, 1, -1, 1);
diff --git a/cogl/cogl/cogl.c b/cogl/cogl/cogl.c
index 562b40d9b1..469a64bb4f 100644
--- a/cogl/cogl/cogl.c
+++ b/cogl/cogl/cogl.c
@@ -73,25 +73,6 @@ _cogl_check_extension (const char *name, char * const *ext)
   return FALSE;
 }
 
-void
-cogl_set_backface_culling_enabled (gboolean setting)
-{
-  _COGL_GET_CONTEXT (ctx, NO_RETVAL);
-
-  if (ctx->legacy_backface_culling_enabled == setting)
-    return;
-
-  ctx->legacy_backface_culling_enabled = setting;
-}
-
-gboolean
-cogl_get_backface_culling_enabled (void)
-{
-  _COGL_GET_CONTEXT (ctx, FALSE);
-
-  return ctx->legacy_backface_culling_enabled;
-}
-
 gboolean
 cogl_has_feature (CoglContext *ctx, CoglFeatureID feature)
 {
diff --git a/cogl/cogl/cogl1-context.h b/cogl/cogl/cogl1-context.h
index 50a07ae905..b36c3e7312 100644
--- a/cogl/cogl/cogl1-context.h
+++ b/cogl/cogl/cogl1-context.h
@@ -79,36 +79,6 @@ cogl_get_option_group (void);
 COGL_EXPORT GCallback
 cogl_get_proc_address (const char *name);
 
-/**
- * cogl_set_backface_culling_enabled:
- * @setting: %TRUE to enable backface culling or %FALSE to disable.
- *
- * Sets whether textures positioned so that their backface is showing
- * should be hidden. This can be used to efficiently draw two-sided
- * textures or fully closed cubes without enabling depth testing. This
- * only affects calls to the cogl_rectangle* family of functions and
- * cogl_vertex_buffer_draw*. Backface culling is disabled by default.
- *
- * Deprecated: 1.16: Use cogl_pipeline_set_cull_face_mode() instead
- */
-COGL_DEPRECATED_FOR (cogl_pipeline_set_cull_face_mode)
-COGL_EXPORT void
-cogl_set_backface_culling_enabled (gboolean setting);
-
-/**
- * cogl_get_backface_culling_enabled:
- *
- * Queries if backface culling has been enabled via
- * cogl_set_backface_culling_enabled()
- *
- * Return value: %TRUE if backface culling is enabled, and %FALSE otherwise
- *
- * Deprecated: 1.16: Use cogl_pipeline_get_cull_face_mode() instead
- */
-COGL_DEPRECATED_FOR (cogl_pipeline_get_cull_face_mode)
-COGL_EXPORT gboolean
-cogl_get_backface_culling_enabled (void);
-
 /**
  * cogl_flush:
  *