Add _android files for building DartVM on Android

runtime/bin/socket_android.cc

Index: runtime/bin/socket_android.cc
diff --git a/runtime/bin/socket_linux.cc b/runtime/bin/socket_android.cc
similarity index 95%
copy from runtime/bin/socket_linux.cc
copy to runtime/bin/socket_android.cc
index b126f5ddcc989c4238d737c0a250235ad92d9025..8a57d014c7ccfc227d507274a55de4385e0fcc7e 100644
--- a/runtime/bin/socket_linux.cc
+++ b/runtime/bin/socket_android.cc
@@ -13,7 +13,7 @@
 
 
 bool Socket::Initialize() {
-  // Nothing to do on Linux.
+  // Nothing to do on Android.
   return true;
 }
 
@@ -123,13 +123,14 @@ bool Socket::GetRemotePeer(intptr_t fd, char *host, intptr_t *port) {
 
 
 void Socket::GetError(intptr_t fd, OSError* os_error) {
-  int len = sizeof(errno);
+  int errorNumber;
+  socklen_t len = sizeof(errorNumber);
   getsockopt(fd,
              SOL_SOCKET,
              SO_ERROR,
-             &errno,
-             reinterpret_cast<socklen_t*>(&len));
-  os_error->SetCodeAndMessage(OSError::kSystem, errno);
+             reinterpret_cast<void*>(&errorNumber),
+             &len);
+  os_error->SetCodeAndMessage(OSError::kSystem, errorNumber);
 }
 
 
@@ -211,7 +212,7 @@ intptr_t ServerSocket::CreateBindListen(const char* host,
 
 
 static bool IsTemporaryAcceptError(int error) {
-  // On Linux a number of protocol errors should be treated as EAGAIN.
+  // On Android a number of protocol errors should be treated as EAGAIN.
   // These are the ones for TCP/IP.
   return (error == EAGAIN) || (error == ENETDOWN) || (error == EPROTO) ||
       (error == ENOPROTOOPT) || (error == EHOSTDOWN) || (error == ENONET) ||