check for libatomic in configure

GNUmakefile.in

@@ -31,7 +31,6 @@ CXX					= @CXX@
 CXXFLAGS			= @CPPFLAGS@ @CXXFLAGS@ @BOOST_CPPFLAGS@
 LDFLAGS				= @LDFLAGS@ @LIBS@ @BOOST_LDFLAGS@
 LIBS				= @LIBS@ \
-					  -latomic \
 					  @BOOST_IOSTREAMS_LIB@ \
 					  @BOOST_DATE_TIME_LIB@
 

configure

@@ -17103,6 +17103,52 @@ fi
 	fi
 
 
+{ $as_echo "$as_me:${as_lineno-$LINENO}: checking for atomic_flag_clear in -latomic" >&5
+$as_echo_n "checking for atomic_flag_clear in -latomic... " >&6; }
+if ${ac_cv_lib_atomic_atomic_flag_clear+:} false; then :
+  $as_echo_n "(cached) " >&6
+else
+  ac_check_lib_save_LIBS=$LIBS
+LIBS="-latomic  $LIBS"
+cat confdefs.h - <<_ACEOF >conftest.$ac_ext
+/* end confdefs.h.  */
+
+/* Override any GCC internal prototype to avoid an error.
+   Use char because int might match the return type of a GCC
+   builtin and then its argument prototype would still apply.  */
+#ifdef __cplusplus
+extern "C"
+#endif
+char atomic_flag_clear ();
+int
+main ()
+{
+return atomic_flag_clear ();
+  ;
+  return 0;
+}
+_ACEOF
+if ac_fn_cxx_try_link "$LINENO"; then :
+  ac_cv_lib_atomic_atomic_flag_clear=yes
+else
+  ac_cv_lib_atomic_atomic_flag_clear=no
+fi
+rm -f core conftest.err conftest.$ac_objext \
+    conftest$ac_exeext conftest.$ac_ext
+LIBS=$ac_check_lib_save_LIBS
+fi
+{ $as_echo "$as_me:${as_lineno-$LINENO}: result: $ac_cv_lib_atomic_atomic_flag_clear" >&5
+$as_echo "$ac_cv_lib_atomic_atomic_flag_clear" >&6; }
+if test "x$ac_cv_lib_atomic_atomic_flag_clear" = xyes; then :
+  cat >>confdefs.h <<_ACEOF
+#define HAVE_LIBATOMIC 1
+_ACEOF
+
+  LIBS="-latomic $LIBS"
+
+fi
+
+
 ac_config_files="$ac_config_files GNUmakefile libcifpp.pc"
 
 cat >confcache <<\_ACEOF

configure.ac

@@ -109,5 +109,7 @@ AX_BOOST_BASE([1.71], [], [
 AX_BOOST_IOSTREAMS
 AX_BOOST_DATE_TIME
 
+AC_CHECK_LIB([atomic], [atomic_flag_clear])
+
 AC_OUTPUT([GNUmakefile
 		   libcifpp.pc])