Revert "check and link against libatomic (#172)" (#177)

This reverts commit 67f064e.

Signed-off-by: Shane Loretz <sloretz@osrfoundation.org>

Author: sloretz

CMakeLists.txt

@@ -11,8 +11,6 @@ if(NOT CMAKE_CXX_STANDARD)
   set(CMAKE_CXX_STANDARD 14)
 endif()
 
-include(CheckLibraryExists)
-
 find_package(ament_cmake_python REQUIRED)
 find_package(ament_cmake_ros REQUIRED)
 
@@ -123,8 +121,6 @@ if(BUILD_TESTING)
 
   find_package(launch_testing_ament_cmake REQUIRED)
 
-  check_library_exists(atomic __atomic_load_8 "" HAVE_LIBATOMICS)
-
   if(ament_cmake_cppcheck_FOUND)
     ament_cppcheck(
       TESTNAME "cppcheck_logging_macros"
@@ -218,11 +214,6 @@ if(BUILD_TESTING)
       LANGUAGE C
   )
   target_link_libraries(test_atomics_executable ${PROJECT_NAME})
-  if(HAVE_LIBATOMICS)
-    target_link_libraries(test_atomics_executable atomic)
-    ament_export_libraries(atomic)
-  endif()
-
   add_test(NAME test_atomics COMMAND test_atomics_executable)
 
   rcutils_custom_add_gmock(test_error_handling test/test_error_handling.cpp