build-sys: test for cxx-11 after AC_USE_SYSTEM_EXTENSIONS

This avoids the following autoconf warning:
configure.ac:89: warning: AC_COMPILE_IFELSE was called before AC_USE_SYSTEM_EXTENSIONS
../../lib/autoconf/specific.m4:368: AC_USE_SYSTEM_EXTENSIONS is expanded from...
configure.ac:89: the top level

diff --git a/configure.ac b/configure.ac
index 77b5ff5..0c38fbb 100644 (file)
--- a/configure.ac
+++ b/configure.ac
@@ -84,9 +84,9 @@ AM_PROG_CC_C_O
 # Only required if you want the WebRTC canceller -- no runtime dep on
 # libstdc++ otherwise
 AC_PROG_CXX
-AX_CXX_COMPILE_STDCXX_11([ext],[optional])
 AC_PROG_GCC_TRADITIONAL
 AC_USE_SYSTEM_EXTENSIONS
+AX_CXX_COMPILE_STDCXX_11([ext],[optional])
 
 # M4