build: remove redundant _GNU_SOURCE definitions

The feature macro _GNU_SOURCE is defined globally,
but there was some remaining useless settings.

The internal definition in config/meson.build is kept,
all other internal definitions of _GNU_SOURCE are removed,
except in examples, which can be built as external applications.
Note: external applications do not inherit of _GNU_SOURCE.

Fixes: 5d7b673d5f ("mk: build with _GNU_SOURCE defined by default")
Fixes: 28188cee2a ("build: enable BSD features visibility for FreeBSD")
Fixes: e6cdc54cc0 ("net/mlx5: add socket server for external tools")
Cc: stable@dpdk.org

Signed-off-by: Thomas Monjalon <thomas@monjalon.net>
Acked-by: Andrew Rybchenko <andrew.rybchenko@oktetlabs.ru>
Acked-by: David Marchand <david.marchand@redhat.com>

app/test/meson.build

@@ -398,8 +398,6 @@ if cc.has_argument('-Wno-format-truncation')
     cflags += '-Wno-format-truncation'
 endif
 
-# specify -D_GNU_SOURCE unconditionally
-cflags += '-D_GNU_SOURCE'
 # Strict-aliasing rules are violated by uint8_t[] to context size casts.
 cflags += '-fno-strict-aliasing'
 

drivers/bus/fslmc/qbman/include/compat.h

@@ -8,9 +8,6 @@
 #ifndef HEADER_COMPAT_H
 #define HEADER_COMPAT_H
 
-#ifndef _GNU_SOURCE
-#define _GNU_SOURCE
-#endif
 #include <stdio.h>
 #include <stdint.h>
 #include <stdlib.h>

drivers/common/dpaax/compat.h

@@ -10,10 +10,6 @@
 #define __COMPAT_H
 
 #include <sched.h>
-
-#ifndef _GNU_SOURCE
-#define _GNU_SOURCE
-#endif
 #include <stdint.h>
 #include <stdlib.h>
 #include <stddef.h>

drivers/common/dpaax/meson.build

@@ -10,7 +10,6 @@ sources = files('dpaax_iova_table.c', 'dpaa_of.c', 'caamflib.c')
 
 includes += include_directories('caamflib')
 
-cflags += ['-D_GNU_SOURCE']
 if cc.has_argument('-Wno-cast-qual')
 	cflags += '-Wno-cast-qual'
 endif

drivers/net/memif/rte_eth_memif.h

@@ -5,10 +5,6 @@
 #ifndef _RTE_ETH_MEMIF_H_
 #define _RTE_ETH_MEMIF_H_
 
-#ifndef _GNU_SOURCE
-#define _GNU_SOURCE
-#endif				/* GNU_SOURCE */
-
 #include <sys/queue.h>
 
 #include <ethdev_driver.h>

drivers/net/mlx5/linux/mlx5_socket.c

@@ -2,10 +2,6 @@
  * Copyright 2019 Mellanox Technologies, Ltd
  */
 
-#ifndef _GNU_SOURCE
-#define _GNU_SOURCE
-#endif
-
 #include <sys/types.h>
 #include <sys/socket.h>
 #include <sys/un.h>