Fix a bug in std::chrono::abs where it would fail when the duration's period had not been reduced.s

llvm-svn: 367120
Cr-Mirrored-From: sso://chromium.googlesource.com/_direct/external/github.com/llvm/llvm-project
Cr-Mirrored-Commit: 736e8aa8ed48fd8c29a909bf616965d0f8677bca
diff --git a/include/chrono b/include/chrono
index 06fa658..51722ad 100644
--- a/include/chrono
+++ b/include/chrono
@@ -1428,7 +1428,7 @@
 >::type
 abs(duration<_Rep, _Period> __d)
 {
-    return __d >= __d.zero() ? __d : -__d;
+    return __d >= __d.zero() ? +__d : -__d;
 }
 #endif