shm: allow for older versions of Linux without MFD_NOEXEC_SEAL
Follow-up on !792 (merged) to support running pulseaudio on older versions of linux that don’t have MFD_NOEXEC_SEAL instead of failing the MEMFD
Follow-up on !792 (merged) to support running pulseaudio on older versions of linux that don’t have MFD_NOEXEC_SEAL instead of failing the MEMFD