[PATCH bpf-next v1 15/19] selftests/bpf: Fix compiling core_reloc.c with musl-libc

[Tony Ambardar <tony.ambardar@xxxxxxxxx>]

The type 'loff_t' is a GNU extension and not exposed by the musl 'fcntl.h'
header unless _GNU_SOURCE is defined. Add this definition to fix errors
seen compiling for mips64el/musl-libc:

  In file included from tools/testing/selftests/bpf/prog_tests/core_reloc.c:4:
  ./bpf_testmod/bpf_testmod.h:10:9: error: unknown type name 'loff_t'
     10 |         loff_t off;
        |         ^~~~~~
  ./bpf_testmod/bpf_testmod.h:16:9: error: unknown type name 'loff_t'
     16 |         loff_t off;
        |         ^~~~~~

Fixes: 6bcd39d366b6 ("selftests/bpf: Add CO-RE relocs selftest relying on kernel module BTF")
Signed-off-by: Tony Ambardar <tony.ambardar@xxxxxxxxx>
---
 tools/testing/selftests/bpf/prog_tests/core_reloc.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/tools/testing/selftests/bpf/prog_tests/core_reloc.c b/tools/testing/selftests/bpf/prog_tests/core_reloc.c
index 47f42e680105..26019313e1fc 100644
--- a/tools/testing/selftests/bpf/prog_tests/core_reloc.c
+++ b/tools/testing/selftests/bpf/prog_tests/core_reloc.c
@@ -1,4 +1,5 @@
 // SPDX-License-Identifier: GPL-2.0
+#define _GNU_SOURCE
 #include <test_progs.h>
 #include "progs/core_reloc_types.h"
 #include "bpf_testmod/bpf_testmod.h"
-- 
2.34.1