Fixed Cygwin CR-munging problem in mailsplit

Do not open mailbox file as fopen(..., "rt")
as this strips CR characters from the diff,
thus breaking the patch context for changes
in CRLF files.

Signed-off-by: Salikh Zakirov <Salikh.Zakirov@Intel.com>
Signed-off-by: Junio C Hamano <junkio@cox.net>

mailsplit.c

@@ -162,7 +162,7 @@ int main(int argc, const char **argv)
 
 	while (*argp) {
 		const char *file = *argp++;
-		FILE *f = !strcmp(file, "-") ? stdin : fopen(file, "rt");
+		FILE *f = !strcmp(file, "-") ? stdin : fopen(file, "r");
 		int file_done = 0;
 
 		if ( !f )