grep: unsigned chars to fix gcc warnings.

commands/grep/binary.c

@@ -37,7 +37,7 @@
 int
 bin_file(FILE *f)
 {
-	char		buf[BUFSIZ];
+	unsigned char	buf[BUFSIZ];
 	size_t		i, m;
 	int		ret = 0;
 
@@ -61,7 +61,7 @@ bin_file(FILE *f)
 int
 gzbin_file(gzFile *f)
 {
-	char		buf[BUFSIZ];
+	unsigned char	buf[BUFSIZ];
 	int		i, m;
 	int		ret = 0;
 

commands/grep/grep.h

@@ -101,7 +101,7 @@ void		 clearqueue(void);
 typedef struct mmfile {
 	int	 fd;
 	size_t	 len;
-	char	*base, *end, *ptr;
+	unsigned char	*base, *end, *ptr;
 } mmf_t;
 
 mmf_t		*mmopen(char *fn, char *mode);