pgindent: ensure all C files end with a newline.

pgindent: ensure all C files end with a newline.

Not only is this good style, but it dodges some obscure bugs within
pg_bsd_indent.  We could try to fix said bugs, but the amount of
effort required seems far out of proportion to the benefit.

Reported-by: Akshay Joshi <akshay.joshi@enterprisedb.com>
Author: Tom Lane <tgl@sss.pgh.pa.us>
Reviewed-by: Andrew Dunstan <andrew@dunslane.net>
Discussion: https://postgr.es/m/CANxoLDfca8O5SkeDxB_j6SVNXd+pNKaDmVmEW+2yyicdU8fy0w@mail.gmail.com