Implement memfd_create syscall decoding

* memfd_create.c: New file.
* Makefile.am (strace_SOURCES): Add it.
* linux/dummy.h (sys_memfd_create): Remove.
* pathtrace.c (pathtrace_match): Add SEN_memfd_create.
* xlat/memfd_create_flags.in: New file.
* tests/memfd_create.c: New file.
* tests/memfd_create.expected: Likewise.
* tests/memfd_create.test: New test.
* tests/Makefile.am: (check_PROGRAMS): Add memfd_create.
(TESTS): Add memfd_create.test.
(EXTRA_DIST): Add memfd_create.expected.
* tests/.gitignore: Add memfd_create.
10 files changed