verilog: formatting: tree_unwrapper: Added line continuation to LookAheadBeyondCurrentLeaf

Added TK_LINE_CONT as another case where the Advancement should
continue, alongside the comments

Signed-off-by: Jan Bylicki <jbylicki@antmicro.com>

verilog/formatting/tree_unwrapper.cc

diff --git a/verilog/formatting/tree_unwrapper.cc b/verilog/formatting/tree_unwrapper.cc
index c8f6176..ef0b748 100644
--- a/verilog/formatting/tree_unwrapper.cc
+++ b/verilog/formatting/tree_unwrapper.cc
@@ -469,7 +469,8 @@
   while (!NextUnfilteredToken()->isEOF()) {
     EatSpaces();
     VLOG(4) << "lookahead token: " << VerboseToken(*NextUnfilteredToken());
-    if (IsComment(verilog_tokentype(NextUnfilteredToken()->token_enum()))) {
+    if (auto next_tok = verilog_tokentype(NextUnfilteredToken()->token_enum());
+        IsComment(next_tok) || next_tok == verilog_tokentype::TK_LINE_CONT) {
       // TODO(fangism): or IsAttribute().  Basically, any token that is not
       // in the syntax tree and not a space.
       AdvanceLastVisitedLeaf();