Philip Chimento authored Jan 11, 2019 and Philip Chimento committed Jan 27, 2019

The GjsPrivate library doesn't use any SpiderMonkey code, only C APIs.
So the files should be compiled with a C compiler, otherwise we get
C++'s stricter typechecks, making it hard to use void* APIs such as
g_steal_pointer().

[skip cpplint] - This shows a diff in the linter output because the
files were renamed.