Bugfix: Negative ints in HTTP's on_body and node.fs.read()

Similar to the error fixed in
9d3ed1bb92.

Reported by Felix Geisendörfer.

src/file.cc

@@ -285,7 +285,8 @@ AfterRawRead(eio_req *req)
     size_t len = req->result;
     Local<Array> array = Array::New(len);
     for (unsigned int i = 0; i < len; i++) {
-      array->Set(Integer::New(i), Integer::New(buf[i]));
+      unsigned char val = reinterpret_cast<const unsigned char*>(buf)[i];
+      array->Set(Integer::New(i), Integer::New(val));
     }
     argv[0] = array;
     argv[1] = Integer::New(req->result);

src/http.cc

@@ -196,7 +196,7 @@ HTTPConnection::on_body (http_parser *parser, const char *buf, size_t len)
     // raw encoding
     Local<Array> array = Array::New(len);
     for (size_t i = 0; i < len; i++) {
-      char val = static_cast<const char*>(buf)[i];
+      unsigned char val = reinterpret_cast<const unsigned char*>(buf)[i];
       array->Set(Integer::New(i), Integer::New(val));
     }
     argv[0] = array;