[m4-common] Add missing AX_CXX_COMPILE_STDCXX macro

[Emmanuele Bassi <ebassi src gnome org>]

commit 1c06eea1420c0a4dd015a6c180431fd65e7af620
Author: Emmanuele Bassi <ebassi gnome org>
Date:   Tue Jul 12 07:08:15 2016 +0100

    Add missing AX_CXX_COMPILE_STDCXX macro
    
    If we don't add ax_cxx_compile_stdcxx.m4, then AX_CXX_COMPILE_STDCXX_11
    won't ever work.

 Makefile.am |    1 +
 1 files changed, 1 insertions(+), 0 deletions(-)
---
diff --git a/Makefile.am b/Makefile.am
index d049298..66f3845 100644
--- a/Makefile.am
+++ b/Makefile.am
@@ -17,6 +17,7 @@ dist_aclocal_DATA = \
        autoconf-archive/m4/ax_compiler_flags_cxxflags.m4               \
        autoconf-archive/m4/ax_compiler_flags_ldflags.m4                \
        autoconf-archive/m4/ax_compiler_flags_gir.m4                    \
+       autoconf-archive/m4/ax_cxx_compile_stdcxx.m4                    \
        autoconf-archive/m4/ax_cxx_compile_stdcxx_11.m4                 \
        autoconf-archive/m4/ax_pkg_check_modules.m4                     \
        autoconf-archive/m4/ax_prog_gjs.m4                              \