Unnecessary (?) anonymous namespace was tripping up MSVC 6.0; the "detail" namespace is fine

[SVN r21249]

libs/format

@@ -1 +1 @@
-Subproject commit c78659f9573f3a353d7a1dfcb96ee1785ce95de3
+Subproject commit 898e7028cdc2f8eed3ff940b9b10856be2df9724