shared: memfd_create: try MFD_NOEXEC_SEAL
Effective from Linux 6.3 onward, this creates the memfd without execute permissions and prevents that setting from ever being changed. A run-time fallback is made to not using MFD_NOEXEC_SEAL when weston compiled on Linux >= 6.3 is run on Linux < 6.3.
Fixes issue #907 (closed)
Signed-off-by: Sami Uddin sami.uddin@astc-design.com