Fix behavior where the non-blocking sendToCliend would block
when there was enough room for the message but not the message header.

Change-Id: I600db04b91e76fa7966c7d8a98e5c56593e1806d
diff --git a/libs/rs/rsContext.cpp b/libs/rs/rsContext.cpp
index dfdeb98..2a94651 100644
--- a/libs/rs/rsContext.cpp
+++ b/libs/rs/rsContext.cpp
@@ -798,7 +798,7 @@
         return false;
     }
     if (!waitForSpace) {
-        if (mIO.mToClient.getFreeSpace() < len) {
+        if (mIO.mToClient.getFreeSpace() <= (len + 8)) {
             // Not enough room, and not waiting.
             return false;
         }