emulator opengles: improve TcpStream throughput

This patch improves the performance of the TcpStream implementation
on the host by disabling the Nagle algorithm, thus improving the
bandwidth of small packets.

When used with the corresponding change in the emulator, this
significantly improves the speed of OpenGLES emulation for many
applications.

Change-Id: Ic09e51ecddf04bc7d667f46e1d260030d5fcad88

tools/emulator/opengl/shared/OpenglCodecCommon/TcpStream.cpp

@@ -23,6 +23,9 @@
 
 #ifndef _WIN32
 #include <netinet/in.h>
+#include <netinet/tcp.h>
+#else
+#include <ws2tcpip.h>
 #endif
 
 TcpStream::TcpStream(size_t bufSize) :
@@ -39,6 +42,15 @@ TcpStream::TcpStream(int sock, size_t bufSize) :
     m_bufsize(bufSize),
     m_buf(NULL)
 {
+    // disable Nagle algorithm to improve bandwidth of small
+    // packets which are quite common in our implementation.
+#ifdef _WIN32
+    DWORD  flag;
+#else
+    int    flag;
+#endif
+    flag = 1;
+    setsockopt( sock, IPPROTO_TCP, TCP_NODELAY, (const char*)&flag, sizeof(flag) );
 }
 
 TcpStream::~TcpStream()