Ensure that all uses of <ctype.h> functions are applied to unsigned-char

values, whether the local char type is signed or not.  This is necessary
for portability.  Per discussion on pghackers around 9/16/00.

src/backend/commands/proclang.c

@@ -31,7 +31,7 @@ case_translate_language_name(const char *input, char *output)
 	int			i;
 
 	for (i = 0; i < NAMEDATALEN && input[i]; ++i)
-		output[i] = tolower(input[i]);
+		output[i] = tolower((unsigned char) input[i]);
 
 	output[i] = '\0';