gl: add a method to check whether DMA modifier is supported in EGL

Part-of: <https://gitlab.freedesktop.org/gstreamer/gstreamer/-/merge_requests/3524>

subprojects/gst-plugins-base/gst-libs/gst/gl/egl/gstglcontext_egl.c

@@ -1826,3 +1826,23 @@ beach:
 #endif
   return FALSE;
 }
+
+/**
+ * gst_gl_context_egl_supports_modifier: (skip)
+ * @context: an EGL #GStGLContext
+ *
+ * Returns: %TRUE if the @context supports the modifiers.
+ *
+ * Since: 1.24
+ */
+gboolean
+gst_gl_context_egl_supports_modifier (GstGLContext * context)
+{
+#if GST_GL_HAVE_DMABUF
+  g_return_val_if_fail (GST_IS_GL_CONTEXT_EGL (context), FALSE);
+
+  return gst_gl_context_egl_fetch_dma_formats (context);
+#else
+  return FALSE;
+#endif
+}

subprojects/gst-plugins-base/gst-libs/gst/gl/egl/gstglcontext_egl.h

@@ -113,6 +113,8 @@ G_GNUC_INTERNAL
 gboolean            gst_gl_context_egl_get_format_modifiers (GstGLContext * context,
                                                              gint fourcc,
                                                              const GArray ** modifiers);
+G_GNUC_INTERNAL
+gboolean            gst_gl_context_egl_supports_modifier     (GstGLContext * context);
 G_END_DECLS
 
 #endif /* __GST_GL_CONTEXT_EGL_H__ */