perf trace: Introduce augmented_filename_syscall_enter() declarator

Helping with tons of boilerplate for syscalls that only want to augment
a filename. Now supporting one such syscall is just a matter of
declaring its arguments struct + using:

  augmented_filename_syscall_enter(openat);

Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: David Ahern <dsahern@gmail.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Wang Nan <wangnan0@huawei.com>
Link: https://lkml.kernel.org/n/tip-ls7ojdseu8fxw7fvj77ejpao@git.kernel.org


Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>