THRIFT-4618: Use poll() instead of select() in C++ TNonblockingServer if available (#1580)

diff --git a/configure.ac b/configure.ac
index 917f6fa..14a8c2e 100755
--- a/configure.ac
+++ b/configure.ac
@@ -640,6 +640,7 @@
 AC_CHECK_HEADERS([sys/socket.h])
 AC_CHECK_HEADERS([sys/time.h])
 AC_CHECK_HEADERS([sys/un.h])
+AC_CHECK_HEADERS([poll.h])
 AC_CHECK_HEADERS([sys/poll.h])
 AC_CHECK_HEADERS([sys/resource.h])
 AC_CHECK_HEADERS([unistd.h])