Documentation cleanup: escape backslashes in Doxygen comments.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@158552 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Lex/Lexer.cpp b/lib/Lex/Lexer.cpp
index 78d58d3..69d21f8 100644
--- a/lib/Lex/Lexer.cpp
+++ b/lib/Lex/Lexer.cpp
@@ -1091,20 +1091,21 @@
 }
 
 /// isHorizontalWhitespace - Return true if this character is horizontal
-/// whitespace: ' ', '\t', '\f', '\v'.  Note that this returns false for '\0'.
+/// whitespace: ' ', '\\t', '\\f', '\\v'.  Note that this returns false for
+/// '\\0'.
 static inline bool isHorizontalWhitespace(unsigned char c) {
   return (CharInfo[c] & CHAR_HORZ_WS) ? true : false;
 }
 
 /// isVerticalWhitespace - Return true if this character is vertical
-/// whitespace: '\n', '\r'.  Note that this returns false for '\0'.
+/// whitespace: '\\n', '\\r'.  Note that this returns false for '\\0'.
 static inline bool isVerticalWhitespace(unsigned char c) {
   return (CharInfo[c] & CHAR_VERT_WS) ? true : false;
 }
 
 /// isWhitespace - Return true if this character is horizontal or vertical
-/// whitespace: ' ', '\t', '\f', '\v', '\n', '\r'.  Note that this returns false
-/// for '\0'.
+/// whitespace: ' ', '\\t', '\\f', '\\v', '\\n', '\\r'.  Note that this returns
+/// false for '\\0'.
 static inline bool isWhitespace(unsigned char c) {
   return (CharInfo[c] & (CHAR_HORZ_WS|CHAR_VERT_WS)) ? true : false;
 }