Use COGL_FLAGS_* for the context's private feature flags

Previously the private feature flags were stored in an enum and we
already had 31 flags. Adding the 32nd flag would presumably make it
add -2³¹ as one of the values which might cause problems. To avoid
this we'll just use an fixed-size array of longs and use indices for
the enum values like we do for the public features.

A slight complication with this is in the CoglDriverDescription where
we were previously using a static intialised value to describe the set
of features that the driver supports. We can't easily do this with the
flags array so instead the features are stored in a fixed-size array
of indices.

Reviewed-by: Robert Bragg <robert@linux.intel.com>
(cherry picked from commit d94cb984e3c93630f3c2e6e3be9d189672aa20f3)

Conflicts:
	cogl/cogl-context-private.h
	cogl/cogl-context.c
	cogl/cogl-private.h
	cogl/cogl-renderer.c
	cogl/driver/gl/cogl-pipeline-opengl.c
	cogl/driver/gl/gl/cogl-driver-gl.c
	cogl/driver/gl/gl/cogl-pipeline-progend-fixed-arbfp.c
	cogl/driver/gl/gles/cogl-driver-gles.c
	cogl/driver/nop/cogl-driver-nop.c

cogl/cogl-renderer.c

@@ -95,16 +95,17 @@ typedef struct _CoglDriverDescription
   CoglDriver id;
   const char *name;
   CoglRendererConstraint constraints;
-  CoglPrivateFeatureFlags private_feature_flags;
+  /* It would be nice to make this a pointer and then use a compound
+   * literal from C99 to initialise it but we probably can't get away
+   * with using C99 here. Instead we'll just use a fixed-size array.
+   * GCC should complain if someone adds an 8th feature to a
+   * driver. */
+  const CoglPrivateFeature private_features[8];
   const CoglDriverVtable *vtable;
   const CoglTextureDriver *texture_driver;
   const char *libgl_name;
 } CoglDriverDescription;
 
-_COGL_STATIC_ASSERT(sizeof (CoglPrivateFeatureFlags) <=
-                    sizeof (uint32_t),
-                    "Private feature flags don't fit in 32 bits");
-
 static CoglDriverDescription _cogl_drivers[] =
 {
 #ifdef HAVE_COGL_GL
@@ -112,9 +113,10 @@ static CoglDriverDescription _cogl_drivers[] =
     COGL_DRIVER_GL,
     "gl",
     0,
-    COGL_PRIVATE_FEATURE_ANY_GL |
-      COGL_PRIVATE_FEATURE_GL_FIXED |
+    { COGL_PRIVATE_FEATURE_ANY_GL,
+      COGL_PRIVATE_FEATURE_GL_FIXED,
       COGL_PRIVATE_FEATURE_GL_PROGRAMMABLE,
+      -1 },
     &_cogl_driver_gl,
     &_cogl_texture_driver_gl,
     COGL_GL_LIBNAME,
@@ -123,8 +125,9 @@ static CoglDriverDescription _cogl_drivers[] =
     COGL_DRIVER_GL3,
     "gl3",
     0,
-    COGL_PRIVATE_FEATURE_ANY_GL |
+    { COGL_PRIVATE_FEATURE_ANY_GL,
       COGL_PRIVATE_FEATURE_GL_PROGRAMMABLE,
+      -1 },
     &_cogl_driver_gl,
     &_cogl_texture_driver_gl,
     COGL_GL_LIBNAME,
@@ -135,9 +138,10 @@ static CoglDriverDescription _cogl_drivers[] =
     COGL_DRIVER_GLES2,
     "gles2",
     COGL_RENDERER_CONSTRAINT_SUPPORTS_COGL_GLES2,
-    COGL_PRIVATE_FEATURE_ANY_GL |
-      COGL_PRIVATE_FEATURE_GL_EMBEDDED |
+    { COGL_PRIVATE_FEATURE_ANY_GL,
+      COGL_PRIVATE_FEATURE_GL_EMBEDDED,
       COGL_PRIVATE_FEATURE_GL_PROGRAMMABLE,
+      -1 },
     &_cogl_driver_gles,
     &_cogl_texture_driver_gles,
     COGL_GLES2_LIBNAME,
@@ -148,9 +152,10 @@ static CoglDriverDescription _cogl_drivers[] =
     COGL_DRIVER_GLES1,
     "gles1",
     0,
-    COGL_PRIVATE_FEATURE_ANY_GL |
-      COGL_PRIVATE_FEATURE_GL_EMBEDDED |
+    { COGL_PRIVATE_FEATURE_ANY_GL,
+      COGL_PRIVATE_FEATURE_GL_EMBEDDED,
       COGL_PRIVATE_FEATURE_GL_FIXED,
+      -1 },
     &_cogl_driver_gles,
     &_cogl_texture_driver_gles,
     COGL_GLES1_LIBNAME,
@@ -161,10 +166,11 @@ static CoglDriverDescription _cogl_drivers[] =
     COGL_DRIVER_WEBGL,
     "webgl",
     0,
-    COGL_PRIVATE_FEATURE_ANY_GL |
-      COGL_PRIVATE_FEATURE_GL_EMBEDDED |
-      COGL_PRIVATE_FEATURE_GL_PROGRAMMABLE |
+    { COGL_PRIVATE_FEATURE_ANY_GL,
+      COGL_PRIVATE_FEATURE_GL_EMBEDDED,
+      COGL_PRIVATE_FEATURE_GL_PROGRAMMABLE,
       COGL_PRIVATE_FEATURE_GL_WEB,
+      -1 },
     &_cogl_driver_gles,
     &_cogl_texture_driver_gles,
     NULL,
@@ -174,7 +180,7 @@ static CoglDriverDescription _cogl_drivers[] =
     COGL_DRIVER_NOP,
     "nop",
     0, /* constraints satisfied */
-    0, /* flags */
+    { -1 },
     &_cogl_driver_nop,
     NULL, /* texture driver */
     NULL /* libgl_name */
@@ -495,6 +501,7 @@ _cogl_renderer_choose_driver (CoglRenderer *renderer,
   const char *libgl_name;
   SatisfyConstraintsState state;
   const CoglDriverDescription *desc;
+  int i;
 
   if (!driver_name)
     driver_name = _cogl_config_driver;
@@ -569,12 +576,17 @@ _cogl_renderer_choose_driver (CoglRenderer *renderer,
   renderer->driver = desc->id;
   renderer->driver_vtable = desc->vtable;
   renderer->texture_driver = desc->texture_driver;
-  renderer->private_feature_flags = desc->private_feature_flags;
   libgl_name = desc->libgl_name;
 
+  memset(renderer->private_features, 0, sizeof (renderer->private_features));
+  for (i = 0; desc->private_features[i] != -1; i++)
+    COGL_FLAGS_SET (renderer->private_features,
+                    desc->private_features[i], TRUE);
+
 #ifndef HAVE_DIRECTLY_LINKED_GL_LIBRARY
 
-  if (renderer->private_feature_flags & COGL_PRIVATE_FEATURE_ANY_GL)
+  if (COGL_FLAGS_GET (renderer->private_features,
+                      COGL_PRIVATE_FEATURE_ANY_GL))
     {
       renderer->libgl_module = g_module_open (libgl_name,
                                               G_MODULE_BIND_LAZY);