Fixed lexical eror when a preprocessor directive is followed by a single line comment that starts with "//*".

This commit fixes a lexical eror when a preprocessor directive is
followed by a single line comment that starts with "//*".

The following code could not be tokenized:

#define LSTFVLES_CPP  //*

It triggers the following error:

net.sourceforge.pmd.lang.ast.TokenMgrError: Lexical error in file
'foo.cpp' at line 2, column 0.  Encountered: <EOF> after : ""

pmd-cpp/etc/grammar/cpp.jj

@@ -174,6 +174,7 @@ SKIP :
 {
    "\n" : DEFAULT
    | "/*" : IN_PREPROCESSOR_OUTPUT_COMMENT
+   | "//" : IN_LINE_COMMENT
 }
 
 <PREPROCESSOR_OUTPUT> MORE: