grpc: Link with libatomic on clang/x86

clang does delegate the atomic<double> calls to libatomic on x86 where
as gcc tries to use intrinsics, its debatable who is right, but it does
seem that clang is safe in case pointer is unaligned

Signed-off-by: Khem Raj <raj.khem@gmail.com>
(cherry picked from commit f7a7a2aafe)
Signed-off-by: Armin Kuster <akuster808@gmail.com>

meta-networking/recipes-devtools/grpc/grpc_1.24.1.bb

@@ -44,6 +44,10 @@ do_configure_prepend_mipsarch() {
     sed -i -e "s/set(_gRPC_ALLTARGETS_LIBRARIES \${CMAKE_DL_LIBS} rt m pthread)/set(_gRPC_ALLTARGETS_LIBRARIES \${CMAKE_DL_LIBS} atomic rt m pthread)/g" ${S}/CMakeLists.txt
 }
 
+do_configure_prepend_toolchain-clang_x86() {
+    sed -i -e "s/set(_gRPC_ALLTARGETS_LIBRARIES \${CMAKE_DL_LIBS} rt m pthread)/set(_gRPC_ALLTARGETS_LIBRARIES \${CMAKE_DL_LIBS} atomic rt m pthread)/g" ${S}/CMakeLists.txt
+}
+
 BBCLASSEXTEND = "native nativesdk"
 
 SYSROOT_DIRS_BLACKLIST_append_class-target = "${baselib}/cmake/grpc"