Fixed case giving incorrect 'File ended in the middle of a comment block' warning

Test case:
```.c++
/// class
class T
{
  public:
  /// Some text
  /// \code{.cpp}
  /// int func() {}
  /// \endcode{.cpp}
  int func() {}
};
```

Cause is the extra `{.cpp}` after `\endcode` which is incorrect, but should
not cause the rest of the code to be skipped.

Author: doxygen

src/commentcnv.l

@@ -705,7 +705,7 @@ SLASHopt [/]*
                                        BEGIN(yyextra->lastCommentContext);
                                      }
                                    }
-<VerbatimCode>[\\@]("enddot"|"endcode"|"endmsc"|"enduml") { /* end of verbatim block */
+<VerbatimCode>[\\@]("enddot"|"endcode"|"endmsc"|"enduml")/("{")? { /* end of verbatim block */
                                      copyToOutput(yyscanner,yytext,yyleng);
 				     if (&yytext[1]==yyextra->blockName)
 				     {