add atomic library to link targets for giotto-ph when compiling with clang

giotto-ph-clang-atomic.patch

diff --git a/CMakeLists.txt b/CMakeLists.txt
index 18bd949..c4e10b7 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -49,6 +49,10 @@ else()
 endif()
 
 target_link_libraries(gph_ripser PRIVATE ${JUNCTION_ALL_LIBRARIES})
+if (CMAKE_CXX_COMPILER_ID MATCHES "Clang")
+	target_link_libraries(gph_ripser PRIVATE atomic)
+endif()
+
 
 #######################################################################
 #                Ripser Lock Free - Coefficient enable                #
@@ -75,6 +79,9 @@ else()
 endif()
 
 target_link_libraries(gph_ripser_coeff PRIVATE ${JUNCTION_ALL_LIBRARIES})
+if (CMAKE_CXX_COMPILER_ID MATCHES "Clang")
+	target_link_libraries(gph_ripser_coeff PRIVATE atomic)
+endif()
 
 #######################################################################
 #                              Collapser                              #