Remove bogus mapping from UTF-8 to SJIS conversion table.

0xc19c is not a valid UTF-8 byte sequence. It doesn't do any harm, AFAICS,
but it's surely not intentional. No backpatching though, just to be sure.

In the passing, also add a file header comment to the file, like the
UCS_to_SJIS.pl script would produce. (The file was originally created with
UCS_to_SJIS.pl, but has been modified by hand since then. That's
questionable, but I'll leave fixing that for later.)

Kyotaro Horiguchi

Discussion: <20160907.155050.233844095.horiguchi.kyotaro@lab.ntt.co.jp>

src/backend/utils/mb/Unicode/utf8_to_sjis.map

@@ -1,5 +1,6 @@
-static const pg_utf_to_local ULmapSJIS[ 7398 ] = {
-  {0xc19c, 0x815f},
+/* src/backend/utils/mb/Unicode/utf8_to_sjis.map */
+
+static const pg_utf_to_local ULmapSJIS[ 7397 ] = {
   {0xc2a2, 0x8191},
   {0xc2a3, 0x8192},
   {0xc2a5, 0x5c},