frr: Fix native clippy failing to load libatomic.so.1

frr's configure links libatomic whenever the toolchain merely has it:

  AC_CHECK_LIB([atomic], [main], [LIBS="$LIBS -latomic"], [], [])

This probe only asks whether -latomic links, never whether frr needs a
symbol from it. On x86-64 the atomics frr uses are inlined, so the
resulting native clippy references no __atomic_* symbol at all, yet
still records a DT_NEEDED on libatomic.so.1.

Nothing prunes it: ASNEEDED is part of TARGET_LDFLAGS only, so native
links get no --as-needed. Nothing can satisfy it either: clippy's
RUNPATH points solely into recipe-sysroot-native, there is no
libatomic-native, and uninative only rewrites the ELF interpreter.

buildtools-extended-tarball ships nativesdk-libatomic, so on hosts using
buildtools (Rocky 8, Alma 8, openSUSE on the autobuilder) the probe
succeeds at link time while the loader cannot find libatomic later, and
the target do_compile dies executing clippy:

  clippy: error while loading shared libraries: libatomic.so.1:
  cannot open shared object file: No such file or directory

Hosts with a system libatomic in the default loader path, such as Ubuntu
with libatomic1 installed, only avoid this by accident.

Link native clippy with --as-needed so the unused libatomic dependency is
dropped, making the frr-native artifact independent of the build host.

Fixes [YOCTO #15590] and [YOCTO #15590]

Signed-off-by: Khem Raj <khem.raj@oss.qualcomm.com>
(cherry picked from commit 1c1e7a0bc7)
Signed-off-by: Anuj Mittal <anuj.mittal@oss.qualcomm.com>

meta-networking/recipes-protocols/frr/frr_10.6.1.bb

@@ -67,6 +67,14 @@ LDFLAGS:append:mipsel = " -latomic"
 LDFLAGS:append:powerpc = " -latomic"
 LDFLAGS:append:riscv32 = " -latomic"
 
+# configure links -latomic whenever the toolchain merely has it
+# (AC_CHECK_LIB([atomic],[main])) rather than when it is needed. buildtools ships
+# libatomic, so clippy gets a DT_NEEDED that the loader cannot resolve later:
+# BUILD_LDFLAGS has no --as-needed, there is no libatomic-native, and uninative
+# only rewrites the interpreter. Hosts without a system libatomic then fail with
+# "clippy: error while loading shared libraries: libatomic.so.1".
+LDFLAGS:append:class-native = " -Wl,--as-needed"
+
 SYSTEMD_PACKAGES = "${PN}"
 SYSTEMD_SERVICE:${PN} = "frr.service"
 SYSTEMD_AUTO_ENABLE = "disable"