Update the copyright headers in most of the C/C++ code consistently use the
GPLv2 copyright message. This allows these files to pass Facebook's internal
Some of the files in fbcode/scm/hgext/cstore/ appear to have actually been
copied from the hg-crew repository, and were not originally authored by
Facebook. I have not modified the copyright statements in these files:
I also have not modified any of the cfastmanifest code.
This corresponds to Facebook diff D5588677.