mesa/main: mark GL_BGRA as color-renderable

The EXT_texture_format_BGRA8888-spec is quite clear that this format is
color-renderable, so let's mark it properly as such.

It should also be texture-filterable, because in the version of OpenGL
ES it was written against all texture-formats were filterable to begin
with.

While we're at it, use the non-EXT version of the enum; it's been in the
headers since OpenGL 1.2...

Reviewed-by: Marek Olšák <marek.olsak@amd.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/27521>

src/mesa/main/genmipmap.c

@@ -87,15 +87,10 @@ _mesa_is_valid_generate_texture_mipmap_internalformat(struct gl_context *ctx,
        *  not specified with an unsized internal format from table 8.3 or a
        *  sized internal format that is both color-renderable and
        *  texture-filterable according to table 8.10."
-       *
-       * GL_EXT_texture_format_BGRA8888 adds a GL_BGRA_EXT unsized internal
-       * format, and includes it in a very similar looking table.  So we
-       * include it here as well.
        */
       return internalformat == GL_RGBA || internalformat == GL_RGB ||
              internalformat == GL_LUMINANCE_ALPHA ||
              internalformat == GL_LUMINANCE || internalformat == GL_ALPHA ||
-             internalformat == GL_BGRA_EXT ||
              (_mesa_is_es3_color_renderable(ctx, internalformat) &&
               _mesa_is_es3_texture_filterable(ctx, internalformat));
    }

src/mesa/main/glformats.c

@@ -4027,6 +4027,9 @@ _mesa_is_es3_color_renderable(const struct gl_context *ctx,
    case GL_RGBA16_SNORM:
       return _mesa_has_EXT_texture_norm16(ctx) &&
              _mesa_has_EXT_render_snorm(ctx);
+   case GL_BGRA:
+      assert(_mesa_has_EXT_texture_format_BGRA8888(ctx));
+      return true;
    default:
       return false;
    }
@@ -4085,6 +4088,9 @@ _mesa_is_es3_texture_filterable(const struct gl_context *ctx,
        *     for the R32F, RG32F, RGB32F, and RGBA32F formats."
        */
       return _mesa_has_OES_texture_float_linear(ctx);
+   case GL_BGRA:
+      assert(_mesa_has_EXT_texture_format_BGRA8888(ctx));
+      return true;
    default:
       return false;
    }