Consolidation of libatomic checks (#3314)

Problem: compiler might not support atomic warning flag

Solution: check before using it

configure.ac

@@ -195,7 +195,6 @@ case "${host_os}" in
         case "${host_os}" in
             *android*)
                 AC_DEFINE(ZMQ_HAVE_ANDROID, 1, [Have Android OS])
-                AC_CHECK_LIB([atomic],[__atomic_load_4],[LIBS="${LIBS} -latomic"]) 
 		libzmq_on_android="yes"
             ;;
         esac
@@ -638,6 +637,10 @@ AM_CONDITIONAL(ON_DEBIAN_KFREEBSD, test "x$libzmq_on_debian_kfreebsd" = "xyes")
 
 # Check for __atomic_Xxx compiler intrinsics
 AC_LANG_PUSH([C++])
+AX_CHECK_COMPILE_FLAG([-Wno-atomic-alignment],
+    [CXXFLAGS+=" -Wno-atomic-alignment"],
+    [],
+    [-Werror])
 LIBZMQ_CHECK_ATOMIC_INTRINSICS([
     AC_DEFINE([ZMQ_HAVE_ATOMIC_INTRINSICS],
               [1],