atomic_bool was missing (just a typedef to atomic<bool>).

git-svn-id: https://llvm.org/svn/llvm-project/libcxx/trunk@171498 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/include/atomic b/include/atomic
index 6dffdb2..4731e4f 100644
--- a/include/atomic
+++ b/include/atomic
@@ -472,6 +472,7 @@
 
 // Atomics for standard typedef types
 
+typedef atomic<bool>               atomic_bool;
 typedef atomic<char>               atomic_char;
 typedef atomic<signed char>        atomic_schar;
 typedef atomic<unsigned char>      atomic_uchar;
@@ -1454,6 +1455,7 @@
 
 // Atomics for standard typedef types
 
+typedef atomic<bool>               atomic_bool;
 typedef atomic<char>               atomic_char;
 typedef atomic<signed char>        atomic_schar;
 typedef atomic<unsigned char>      atomic_uchar;