Fix gcc 4.0 warnings.

diff --git a/programs/winetest/send.c b/programs/winetest/send.c
index 2e6e11c..0306754 100644
--- a/programs/winetest/send.c
+++ b/programs/winetest/send.c
@@ -107,7 +107,7 @@
     SOCKET s;
     FILE *f;
 #define BUFLEN 8192
-    unsigned char buffer[BUFLEN+1];
+    char buffer[BUFLEN+1];
     size_t bytes_read, total, filesize;
     char *str;
     int ret;