Merge pull request #734 from timsong-cpp/patch-3

[class.path] escape backslash in character literal

Author: jwakely

source/iostreams.tex

@@ -10645,7 +10645,7 @@
 \tcode{preferred_separator} is the slash character (\tcode{'/'}).
 For Windows based operating systems,
 \tcode{value_type} is \tcode{wchar_t} and
-\tcode{preferred_separator} is the backslash character (\tcode{L'\textbackslash'}).
+\tcode{preferred_separator} is the backslash character (\tcode{L'\textbackslash\textbackslash'}).
 \exitexample
 
 \rSec3[path.generic]{Generic pathname format}