[OpenSIPS-Devel] [OpenSIPS/opensips] 54cf93: Fix compiler warnings with -DUSE_FUTEX

[Liviu Chircu]

  Branch: refs/heads/3.2
  Home:   https://github.com/OpenSIPS/opensips
  Commit: 54cf93cc6aaa08497d6ade4fcb3f67b5e7fc0708
      https://github.com/OpenSIPS/opensips/commit/54cf93cc6aaa08497d6ade4fcb3f67b5e7fc0708
  Author: Liviu Chircu <liviu at opensips.org>
  Date:   2021-06-17 (Thu, 17 Jun 2021)

  Changed paths:
    M db/db_ut.c
    M serialize.c

  Log Message:
  -----------
  Fix compiler warnings with -DUSE_FUTEX

Specifically:
    futex_lock.h:78: warning: implicit declaration of function ‘syscall’

This warning appears since glibc version 2.19, along with the
introduction of the _DEFAULT_SOURCE FTM, which is a macro that seems to
be additionally required when defining any of the previous FTMs...

man feature_test_macros

(cherry picked from commit 24c8ee9ed38ccc41ef45dce3065b9d88cb959782)