[NFC][libcxx] Remove trailing whitespace

It's incredibly annoying when trying to create diffs

llvm-svn: 361981
diff --git a/libcxx/include/initializer_list b/libcxx/include/initializer_list
index 6c4493b7..893736f 100644
--- a/libcxx/include/initializer_list
+++ b/libcxx/include/initializer_list
@@ -82,7 +82,7 @@
     _LIBCPP_INLINE_VISIBILITY
     _LIBCPP_CONSTEXPR_AFTER_CXX11
     size_t    size()  const _NOEXCEPT {return __size_;}
-    
+
     _LIBCPP_INLINE_VISIBILITY
     _LIBCPP_CONSTEXPR_AFTER_CXX11
     const _Ep* begin() const _NOEXCEPT {return __begin_;}