Rename C files to .c in GCC source

[Jonathan Wakely]

On 30 January 2015 at 21:39, DJ Delorie wrote:
>
> pinskia@gmail.com writes:
>> No because they are c++ code so capital C is correct.
>
> However, we should avoid relying on case-sensitive file systems
> (Windows) and use .cc or .cxx for C++ files ("+" is not a valid file
> name character on Windows, so we can't use .c++).

These files are only compiled by GCC's own build system, with GCC's
own makefiles, so we know we invoke the C++ compiler and so the
language isn't inferred from the file extension, and so we aren't
relying on case-sensitive file systems.