Added FD_CLOEXEC flag to client/server socket file descriptors

runtime/bin/socket_linux.cc

Index: runtime/bin/socket_linux.cc
diff --git a/runtime/bin/socket_linux.cc b/runtime/bin/socket_linux.cc
index 896a9da069497bda67f02e03bc55b4a6831ebaf8..89dd267b6dace61675b6fb74c15b92b97fe54e1e 100644
--- a/runtime/bin/socket_linux.cc
+++ b/runtime/bin/socket_linux.cc
@@ -29,6 +29,7 @@ intptr_t Socket::CreateConnect(const char* host, const intptr_t port) {
     return -1;
   }
 
+  FDUtils::SetCloseOnExec(fd);
   FDUtils::SetNonBlocking(fd);
 
   static const size_t kTempBufSize = 1024;
@@ -191,6 +192,8 @@ intptr_t ServerSocket::CreateBindListen(const char* host,
     return -1;
   }
 
+  FDUtils::SetCloseOnExec(fd);
+
   int optval = 1;
   TEMP_FAILURE_RETRY(
       setsockopt(fd, SOL_SOCKET, SO_REUSEADDR, &optval, sizeof(optval)));