[libcxx] Fix whitespace error

Cr-Mirrored-From: https://chromium.googlesource.com/external/github.com/llvm/llvm-project
Cr-Mirrored-Commit: afe8ca867337f5c0e6d1665096e400686a64bef9
diff --git a/docs/FeatureTestMacroTable.rst b/docs/FeatureTestMacroTable.rst
index 1dbeb21..f5c6e5b 100644
--- a/docs/FeatureTestMacroTable.rst
+++ b/docs/FeatureTestMacroTable.rst
@@ -184,7 +184,7 @@
     ------------------------------------------------- -----------------
     ``__cpp_lib_constexpr_swap_algorithms``           *unimplemented*  
     ------------------------------------------------- -----------------
-    ``__cpp_lib_constexpr_utility ``                  ``201811L``      
+    ``__cpp_lib_constexpr_utility``                   ``201811L``      
     ------------------------------------------------- -----------------
     ``__cpp_lib_destroying_delete``                   ``201806L``      
     ------------------------------------------------- -----------------