BUILD: makefile: simplify detection of libatomic
We've had libatomic enabled on arm and aarch64 for some Raspberry PI
while usually it's not needed, but it was a bit arbitrary and in
issue #1455 it was reported that RISCV requires it for single-byte
atomics.
This changes the approach to detect the explicit requirement of
external functions for the builtins, as reported with *_LOCK_FREE=1.
If any of the atomics requires libatomic, it will be used. Older
compilers do not report any such atomic as they use sync_* instead
and will not match it nor include libatomic (which usually is not
present there).
On x86, the rules depend on -march. i386 uses LOCK_FREE=1 for all of
them. i486 uses it only for the 8-byte CAS and i586 doesn't require
it at all. For this reason, the build flags are used during the test.
This was tested with armv7, aarch64, mips, riscv, i
(cherry picked from commit 70c268b4dae1efd184448c385ce47277b0563d1f)
Signed-off-by: Christopher Faulet <cfaulet@haproxy.com>
1 file changed