eglimage: Fix memory leak Also free the GstEGLImage struct allocated by g_new0. Fixes #661 Cherry picked from upstream master: https://gitlab.freedesktop.org/gstreamer/gst-plugins-base/commit/94984e13a9208b0b6d69dea597f42b225ef1f784 Change-Id: I790e5ab89cdf3e7584a5f0a02950e8d0fd237b48