[NFC][libcxx] Remove trailing whitespace

It's incredibly annoying when trying to create diffs

llvm-svn: 361981
Cr-Mirrored-From: sso://chromium.googlesource.com/_direct/external/github.com/llvm/llvm-project
Cr-Mirrored-Commit: a2a1ec27d0e799725cdd41f8456deb9a49433e2d
diff --git a/include/future b/include/future
index 50bdd2d..24396e7 100644
--- a/include/future
+++ b/include/future
@@ -2015,7 +2015,7 @@
               class = typename enable_if
               <
                   !is_same<
-                      typename __uncvref<_Fp>::type, 
+                      typename __uncvref<_Fp>::type,
                       packaged_task
                       >::value
                   >::type
@@ -2026,7 +2026,7 @@
               class = typename enable_if
               <
                   !is_same<
-                      typename __uncvref<_Fp>::type, 
+                      typename __uncvref<_Fp>::type,
                       packaged_task
                       >::value
                   >::type
@@ -2144,7 +2144,7 @@
               class = typename enable_if
               <
                   !is_same<
-                      typename __uncvref<_Fp>::type, 
+                      typename __uncvref<_Fp>::type,
                       packaged_task
                       >::value
                   >::type
@@ -2155,11 +2155,11 @@
               class = typename enable_if
               <
                   !is_same<
-                      typename __uncvref<_Fp>::type, 
+                      typename __uncvref<_Fp>::type,
                       packaged_task
                       >::value
                   >::type
-              >    
+              >
         _LIBCPP_INLINE_VISIBILITY
         packaged_task(allocator_arg_t, const _Allocator& __a, _Fp&& __f)
              : __f_(allocator_arg, __a, _VSTD::forward<_Fp>(__f)),