Fix assorted bugs in contrib/unaccent's configuration file parsing.

Make it use t_isspace() to identify whitespace, rather than relying on
sscanf which is known to get it wrong on some platform/locale combinations.
Get rid of fixed-size buffers.  Make it actually continue to parse the file
after ignoring a line with untranslatable characters, as was obviously
intended.

The first of these issues is per gripe from J Smith, though not exactly
either of his proposed patches.

contrib/unaccent/unaccent.c

@@ -91,35 +91,83 @@ initSuffixTree(char *filename)
 
 	do
 	{
-		char		src[4096];
-		char		trg[4096];
-		int			srclen;
-		int			trglen;
-		char	   *line = NULL;
-
+		/*
+		 * pg_do_encoding_conversion() (called by tsearch_readline()) will
+		 * emit exception if it finds untranslatable characters in current
+		 * locale. We just skip such lines, continuing with the next.
+		 */
 		skip = true;
 
 		PG_TRY();
+		{
+			char	   *line;
+
+			while ((line = tsearch_readline(&trst)) != NULL)
 			{
 				/*
-			 * pg_do_encoding_conversion() (called by tsearch_readline()) will
-			 * emit exception if it finds untranslatable characters in current
-			 * locale. We just skip such characters.
+				 * The format of each line must be "src trg" where src and trg
+				 * are sequences of one or more non-whitespace characters,
+				 * separated by whitespace.  Whitespace at start or end of
+				 * line is ignored.
 				 */
-			while ((line = tsearch_readline(&trst)) != NULL)
+				int			state;
+				char	   *ptr;
+				char	   *src = NULL;
+				char	   *trg = NULL;
+				int			ptrlen;
+				int			srclen = 0;
+				int			trglen = 0;
+
+				state = 0;
+				for (ptr = line; *ptr; ptr += ptrlen)
+				{
+					ptrlen = pg_mblen(ptr);
+					/* ignore whitespace, but end src or trg */
+					if (t_isspace(ptr))
 					{
-				if (sscanf(line, "%s\t%s\n", src, trg) != 2)
+						if (state == 1)
+							state = 2;
+						else if (state == 3)
+							state = 4;
 						continue;
+					}
+					switch (state)
+					{
+						case 0:
+							/* start of src */
+							src = ptr;
+							srclen = ptrlen;
+							state = 1;
+							break;
+						case 1:
+							/* continue src */
+							srclen += ptrlen;
+							break;
+						case 2:
+							/* start of trg */
+							trg = ptr;
+							trglen = ptrlen;
+							state = 3;
+							break;
+						case 3:
+							/* continue trg */
+							trglen += ptrlen;
+							break;
+						default:
+							/* bogus line format */
+							state = -1;
+							break;
+					}
+				}
 
-				srclen = strlen(src);
-				trglen = strlen(trg);
-
+				if (state >= 3)
 					rootSuffixTree = placeChar(rootSuffixTree,
 											   (unsigned char *) src, srclen,
 											   trg, trglen);
-				skip = false;
+
 				pfree(line);
 			}
+			skip = false;
 		}
 		PG_CATCH();
 		{