Fix __thread detection (#8722)

Signed-off-by: Austin Seipp <austin@well-typed.com>

configure.ac

@@ -867,11 +867,11 @@ AC_COMPILE_IFELSE(
   [ AC_LANG_SOURCE([[__thread int tester = 0;]]) ],
   [
    AC_MSG_RESULT(yes)
-   AC_DEFINE([CC_SUPPORTS_TLS],[0],[Define to 1 if __thread is supported])
+   AC_DEFINE([CC_SUPPORTS_TLS],[1],[Define to 1 if __thread is supported])
   ],
   [
    AC_MSG_RESULT(no)
-   AC_DEFINE([CC_SUPPORTS_TLS],[1],[Define to 1 if __thread is supported])
+   AC_DEFINE([CC_SUPPORTS_TLS],[0],[Define to 1 if __thread is supported])
   ])