configure.ac: add option --enable-thread-tls to manage thread ssl support

Add option --enable-thread-tls to manage the including of thread
local storage, so we could explicitly disable it.

Upstream-Status: Pending

Signed-off-by: Hongxu Jia <hongxu.jia@windriver.com>
---
 configure.ac | 17 +++++++++++------
 1 file changed, 11 insertions(+), 6 deletions(-)

Index: syslog-ng-3.15.1/configure.ac
===================================================================
--- syslog-ng-3.15.1.orig/configure.ac
+++ syslog-ng-3.15.1/configure.ac
@@ -190,6 +190,9 @@ AC_ARG_ENABLE(gprof,
 AC_ARG_ENABLE(memtrace,
               [  --enable-memtrace   Enable alternative leak debugging code.])
 
+AC_ARG_ENABLE(thread-tls,
+              [  --enable-thread-tls        Enable Thread Local Storage support.],,enable_thread_tls="no")
+
 AC_ARG_ENABLE(dynamic-linking,
               [  --enable-dynamic-linking        Link everything dynamically.],,enable_dynamic_linking="auto")
 
@@ -591,12 +594,14 @@ dnl ***************************************************************************
 dnl Is the __thread keyword available?
 dnl ***************************************************************************
 
-AC_LINK_IFELSE([AC_LANG_PROGRAM(
-[[#include <pthread.h>
-__thread int a;
-]],
-[a=0;])],
-[ac_cv_have_tls=yes; AC_DEFINE_UNQUOTED(HAVE_THREAD_KEYWORD, 1, "Whether Thread Local Storage is supported by the system")])
+if test "x$enable_thread_tls" != "xno"; then
+    AC_LINK_IFELSE([AC_LANG_PROGRAM(
+    [[#include <pthread.h>
+    __thread int a;
+    ]],
+    [a=0;])],
+    [ac_cv_have_tls=yes; AC_DEFINE_UNQUOTED(HAVE_THREAD_KEYWORD, 1, "Whether Thread Local Storage is supported by the system")])
+fi
 
 dnl ***************************************************************************
 dnl How to do static linking?