As Andrew pointed out: "GPL license states each file should have attribution ...." so I checked into GIT the addition of missing GPL information for the guicast subdirectory and am working on the cinelerra subdirectory and eventually plugins subdirectory.  Some notes:

1) When header missing, first checked to see if file exists in Cinelerra HV-8 or CV.  If files existed there but no header, used header in like files.  For example, bccmodels.inc in HV-8 had no header but bccmodels.C did, so used the same one.

2) Files, like bootstrap.c, that exist in HV and have no header, I left unchanged because I have no idea where this file came from and it has an extension of lower case "c" instead of upper case "C".

3) Any file in Cinelerra-HV that did not have the Copyright/Name/Year, I did not change in CinGG, so that it would match.

If Andrew has time to verify and thinks something should have been done differently, please let me know.