clang-format: Change location of stashed token

[jpienaar]

Summary

LessLess and GreaterGreater are turned into two tokens via the stashed token approach. The location of the stashed token (the second Less or Greater) was assumed to be one past the first Less or Greater. This does not hold in cases such as
printf "\\\\\x0a<<<" | clang-format
Where LessLess is considered a token of length 4 and the second Less (post splitting) starts at an offset of 3 and not 1 from the first one. This results in an error when attempting to insert a space between the first and second Less.

[djasper]

Looks good. Thanks.

lib/Format/Format.cpp

     // Create a synthesized second '>' or '<' token.
     Token Tok = FormatTok->Tok;
     StringRef TokenText = FormatTok->TokenText;
 
     unsigned OriginalColumn = FormatTok->OriginalColumn;
     FormatTok = new (Allocator.Allocate()) FormatToken;
     FormatTok->Tok = Tok;
     SourceLocation TokLocation =
-        FormatTok->Tok.getLocation().getLocWithOffset(1);
+        FormatTok->Tok.getLocation().getLocWithOffset(Tok.getLength() - 1);
+    FormatTok->Tok.setLocation(TokLocation);
     FormatTok->WhitespaceRange = SourceRange(TokLocation, TokLocation);
     FormatTok->TokenText = TokenText;
     FormatTok->ColumnWidth = 1;
-    FormatTok->OriginalColumn = OriginalColumn;
+    FormatTok->OriginalColumn = OriginalColumn + 1;
+
     return FormatTok;
   }
 
   FormatToken *getNextToken() {
     if (GreaterStashed) {
       GreaterStashed = false;
       return getStashedToken();
     }

unittests/Format/FormatTest.cpp

   EXPECT_EQ("f<param><<<1, 1>>>();",
             format("f< param > <<< 1, 1 >>> ();"));
   verifyFormat("aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa"
                "aaaaaaaaaaa<<<\n    1, 1>>>();");
 }
 
 TEST_F(FormatTest, MergeLessLessAtEnd) {
   verifyFormat("<<");
+  EXPECT_EQ("< < <", format("\\\n<<<"));
   verifyFormat("aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa"
                "aaallvm::outs() <<");
   verifyFormat("aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa"
                "aaaallvm::outs()\n    <<");
 }
 
 TEST_F(FormatTest, HandleUnbalancedImplicitBracesAcrossPPBranches) {
   std::string code = "#if A\n"