compiler: Handle newlines in general comments.

On comments, the specification says
(http://golang.org/ref/spec#Comments): General comments start with the
character sequence /* and continue through the character sequence */.
A general comment containing one or more newlines acts like a newline,
otherwise it acts like a space.

Fixes golang/go#11528.

Change-Id: I8a44c68e5b0d41964191c9599493c40d1a1ce500
Reviewed-on: https://go-review.googlesource.com/13064
Reviewed-by: Ian Lance Taylor <[email protected]>

Author: Chris Manghane

go/lex.cc

@@ -600,8 +600,14 @@ Lex::next_token()
 		{
 		  this->lineoff_ = p + 2 - this->linebuf_;
 		  Location location = this->location();
-		  if (!this->skip_c_comment())
+                  bool found_newline = false;
+		  if (!this->skip_c_comment(&found_newline))
 		    return Token::make_invalid_token(location);
+                  if (found_newline && this->add_semi_at_eol_)
+                    {
+                      this->add_semi_at_eol_ = false;
+                      return this->make_operator(OPERATOR_SEMICOLON, 1);
+                    }
 		  p = this->linebuf_ + this->lineoff_;
 		  pend = this->linebuf_ + this->linesize_;
 		}
@@ -1621,7 +1627,7 @@ Lex::one_character_operator(char c)
 // Skip a C-style comment.
 
 bool
-Lex::skip_c_comment()
+Lex::skip_c_comment(bool* found_newline)
 {
   while (true)
     {
@@ -1642,6 +1648,9 @@ Lex::skip_c_comment()
 	      return true;
 	    }
 
+          if (p[0] == '\n')
+            *found_newline = true;
+
 	  this->lineoff_ = p - this->linebuf_;
 	  unsigned int c;
 	  bool issued_error;

go/lex.h

@@ -469,7 +469,7 @@ class Lex
   one_character_operator(char);
 
   bool
-  skip_c_comment();
+  skip_c_comment(bool* found_newline);
 
   void
   skip_cpp_comment();