[patch] Fixed unsigned char compare in remote-sds.c

[Andrew Cagney]

Hello,

I've committed the attached fairly obvious fix.  On some platforms, CHAR 
is unsigned which results in the statement:

	int readchar();
	char c;

	while ((c = readchar()) >= 0)

being pretty useless - ``c'', an unsigned char, is always >= 0.

	enjoy,
		Andrew