tools lib bpf: Provide wrapper for strerror_r to build in !_GNU_SOURCE systems

Same problem that got fixed in a similar fashion in tools/perf/ in
c8b5f2c96d1b ("tools: Introduce str_error_r()"), fix it in the same
way, licensing needs to be sorted out to libbpf to use libapi, so,
for this simple case, just get the same wrapper in tools/lib/bpf.

This makes libbpf and its users (bpftool, selftests, perf) to build
again in Alpine Linux 3.[45678] and edge.

Acked-by: Alexei Starovoitov <[email protected]>
Cc: Adrian Hunter <[email protected]>
Cc: Daniel Borkmann <[email protected]>
Cc: David Ahern <[email protected]>
Cc: Hendrik Brueckner <[email protected]>
Cc: Jakub Kicinski <[email protected]>
Cc: Jiri Olsa <[email protected]>
Cc: Martin KaFai Lau <[email protected]>
Cc: Namhyung Kim <[email protected]>
Cc: Quentin Monnet <[email protected]>
Cc: Thomas Richter <[email protected]>
Cc: Wang Nan <[email protected]>
Cc: Yonghong Song <[email protected]>
Fixes: 1ce6a9fc1549 ("bpf: fix build error in libbpf with EXTRA_CFLAGS="-Wp, -D_FORTIFY_SOURCE=2 -O2"")
Link: https://lkml.kernel.org/r/[email protected]
Signed-off-by: Arnaldo Carvalho de Melo <[email protected]>

1 files changed, 6 insertions, 0 deletions

diff --git a/tools/lib/bpf/str_error.h b/tools/lib/bpf/str_error.h
new file mode 100644
index 000000000000..355b1db571d1
--- /dev/null
+++ b/tools/lib/bpf/str_error.h
@@ -0,0 +1,6 @@
+// SPDX-License-Identifier: LGPL-2.1
+#ifndef BPF_STR_ERROR
+#define BPF_STR_ERROR
+
+char *str_error(int err, char *dst, int len);
+#endif // BPF_STR_ERROR