Fix build on old 32 bit Centos (kernel 2.6.18)

cmake/os/Linux.cmake

@@ -46,3 +46,10 @@ IF(HAVE_DECL_SHM_HUGETLB)
   SET(HUGETLB_USE_PROC_MEMINFO 1)
   SET(HAVE_LARGE_PAGE_OPTION 1)
 ENDIF()
+
+IF(CMAKE_SIZEOF_VOID_P EQUAL 4 AND CMAKE_SYSTEM_PROCESSOR MATCHES "86")
+  SET(CMAKE_C_FLAGS "${CMAKE_C_FLAGS} -march=i686")
+  SET(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -march=i686")
+  SET(CMAKE_REQUIRED_FLAGS "${CMAKE_REQUIRED_FLAGS} -march=i686")
+ENDIF()
+

sql/threadpool_unix.cc

@@ -190,6 +190,10 @@ static void set_next_timeout_check(ulonglong abstime);
 */
 
 #if defined (__linux__)
+#ifndef EPOLLRDHUP
+/* Early 2.6 kernel did not have EPOLLRDHUP */
+#define EPOLLRDHUP 0
+#endif
 static int io_poll_create()
 {
   return epoll_create(1);