libatomic_ops support

auto/lib/make

diff --git a/auto/lib/make b/auto/lib/make
index 170311c..f22767e 100644
--- a/auto/lib/make
+++ b/auto/lib/make
@@ -22,6 +22,10 @@
     . auto/lib/zlib/make
 fi
 
+if [ $NGX_LIBATOMIC != NO -a $NGX_LIBATOMIC != YES ]; then
+    . auto/lib/libatomic/make
+fi
+
 if [ $USE_PERL = YES ]; then
     . auto/lib/perl/make
 fi