Add patch to check if platform requires linking to atomic

H/HELICS/build_tarballs.jl

@@ -20,6 +20,7 @@ HELICS_VERSION = v"3.6.0"
 HELICS_SHA = "e111ac5d92e808f27e330afd1f8b8ca4d86adf6ccd74e3280f2d40fb3e0e2ce9"
 
 sources = [
+    DirectorySource("./bundled"),
     ArchiveSource("https://github.com/GMLC-TDC/HELICS/releases/download/v$HELICS_VERSION/Helics-v$HELICS_VERSION-source.tar.gz",
                   "$HELICS_SHA"),
     ArchiveSource("https://github.com/phracker/MacOSX-SDKs/releases/download/10.15/MacOSX10.15.sdk.tar.xz",
@@ -42,6 +43,8 @@ apk del cmake
 
 cd $WORKSPACE/srcdir
 
+atomic_patch -p1 $WORKSPACE/srcdir/patches/link-atomic.patch
+
 cmake -B build \
    -DCMAKE_FIND_ROOT_PATH="${prefix}" \
    -DCMAKE_INSTALL_PREFIX="${prefix}" \

H/HELICS/bundled/patches/link-atomic.patch

@@ -0,0 +1,30 @@
+--- a/CMakeLists.txt
++++ b/CMakeLists.txt
+@@ -387,6 +387,27 @@ if(HELICS_ENABLE_MPI_CORE)
+     list(APPEND VCPKG_MANIFEST_FEATURES "mpi")
+ endif()
+
++# -------------------------------------------------------------
++# check if atomic needs linking
++# -------------------------------------------------------------
++
++check_cxx_source_compiles("
++#include <atomic>
++#include <cstdint>
++std::atomic<uint8_t> n8 (0);
++std::atomic<uint64_t> n64 (0);
++int main() {
++uint8_t i = n8.load(std::memory_order_relaxed);
++uint64_t j = n64.load(std::memory_order_relaxed);
++return std::atomic_is_lock_free(&n8)
++     & std::atomic_is_lock_free(&n64);
++}"
++LIBATOMIC_NOT_NEEDED)
++
++IF (NOT LIBATOMIC_NOT_NEEDED)
++    target_link_libraries(helics_base INTERFACE atomic)
++endif()
++
+ # -------------------------------------------------------------
+ # finding MPI
+ # -------------------------------------------------------------