Fix return types of sendMessageOnSocket/receiveMessageFromSocket

recvmsg() and sendmsg() return ssize_t but the wrapper functions
returned int. Fix the return type.

Bug: 250685929
Test: atest rpcBinderTest
Change-Id: Ia3f7f58e286f24a8711aed97d9bc2b3cf6b78f0d
diff --git a/libs/binder/RpcTransportRaw.cpp b/libs/binder/RpcTransportRaw.cpp
index 1912d14..cd067bf 100644
--- a/libs/binder/RpcTransportRaw.cpp
+++ b/libs/binder/RpcTransportRaw.cpp
@@ -61,7 +61,8 @@
             override {
         bool sentFds = false;
         auto send = [&](iovec* iovs, int niovs) -> ssize_t {
-            int ret = sendMessageOnSocket(mSocket, iovs, niovs, sentFds ? nullptr : ancillaryFds);
+            ssize_t ret =
+                    sendMessageOnSocket(mSocket, iovs, niovs, sentFds ? nullptr : ancillaryFds);
             sentFds |= ret > 0;
             return ret;
         };