add fortified implementations of send/sendto

Bug: None
Test: Bullhead builds+boots; CtsBionicTestCases passes.
Change-Id: I2f137a100f679f7f2145d84b2f29ddd3e96a36ae
diff --git a/libc/bionic/send.cpp b/libc/bionic/send.cpp
index 2e5d457..8f175d3 100644
--- a/libc/bionic/send.cpp
+++ b/libc/bionic/send.cpp
@@ -28,6 +28,6 @@
 
 #include <sys/socket.h>
 
-ssize_t send(int socket, const void* buf, size_t len, int flags) {
+ssize_t send(int socket, const void* buf, size_t len, int flags) __overloadable {
   return sendto(socket, buf, len, flags, NULL, 0);
 }