recognize Comma as a fake token to be dropped by sgrep

Fake commas are kept around in the unparsing process. Remove them in the sgrep (*) case with the other fake tokens.

It is not possible to have a proper test case for this issue because * doesn't change the code. The problem can be seen using the included test case and the command line argument --save-tmp-files on a version of spatch from before this commit. Looking at the generated file in /tmp shows the extra comma. The fake comma on this line causes a - to be printed in the generated diff.

Reported-by: Markus Elfring Markus.Elfring@web.de