Disable fcntl bitwise enum in default build

Disable fcntl bitwise enum in default build

Only generate the bitwise enumerations when
CONFIG_LTTNG_EXPERIMENTAL_BITWISE_ENUM is enabled, so the default build
does not generate traces which lead to warnings when viewed with
babeltrace 1.x and babeltrace 2 with default options.

Original commit:

  commit c1c07d681a68ba37da066d6f0456129957073169
  Author: Geneviève Bastien <gbastien+lttng@versatic.net>
  Date:   Wed Mar 11 12:38:51 2020 -0400

    syscalls: Make the cmd field of fcntl an enum

Use the non-override system call tracing implementation when the enum is
not used.

Change-Id: I4c650d40a14b1c56ada0ed9aae1877364d0c4580
Signed-off-by: Michael Jeanson <mjeanson@efficios.com>
Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>