tools/net: Handle files which don't support sendfile

This adds a fallback read / write model.

Tested: ran against non-sendfile compatible file and it sent to the BMC successfully.

Change-Id: I6fd781ad19cd37376ca90743f799988e50ed460e
Signed-off-by: William A. Kennington III <wak@google.com>
Signed-off-by: Willy Tu <wltu@google.com>
diff --git a/internal/sys.cpp b/internal/sys.cpp
index b4a1ffc..9024666 100644
--- a/internal/sys.cpp
+++ b/internal/sys.cpp
@@ -104,6 +104,11 @@
     return ::connect(sockfd, addr, addrlen);
 }
 
+ssize_t SysImpl::send(int sockfd, const void* buf, size_t len, int flags) const
+{
+    return ::send(sockfd, buf, len, flags);
+}
+
 ssize_t SysImpl::sendfile(int out_fd, int in_fd, off_t* offset,
                           size_t count) const
 {