Re: New compiler warnings in buildfarm

Sometime in the last month or so, flaviventris's bleeding-edge
version of gcc has started whining[1] about truncation of a
string literal's implicit trailing '\0' in contexts like this:

../pgsql/src/backend/commands/copyto.c:106:41: warning: initializer-string for array of 'char' is too long [-Wunterminated-string-initialization]
  106 | static const char BinarySignature[11] = "PGCOPY\n\377\r\n\0";
      |                                         ^~~~~~~~~~~~~~~~~~~~

../pgsql/src/backend/utils/adt/numutils.c:29:1: warning: initializer-string for array of 'char' is too long [-Wunterminated-string-initialization]
   29 | "00" "01" "02" "03" "04" "05" "06" "07" "08" "09"
      | ^~~~

Presumably this'll appear in less-bleeding-edge releases in a
few months' time.

In the BinarySignature case, we could silence it in at least two ways.
We could remove the explicit trailing \0 and rely on the implicit one:

-static const char BinarySignature[11] = "PGCOPY\n\377\r\n\0";
+static const char BinarySignature[11] = "PGCOPY\n\377\r\n";

Or just drop the unnecessary array length specification: