[pangomm] Build: Require C++14 instead of C++11.

[Murray Cumming <murrayc src gnome org>]

commit 62e91258f1de8639189c022ea15576e43cca7ad3
Author: Murray Cumming <murrayc murrayc com>
Date:   Mon Nov 14 10:46:22 2016 +0100

    Build: Require C++14 instead of C++11.
    
    Because we now use a glibmm that requires C++14.

 configure.ac |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)
---
diff --git a/configure.ac b/configure.ac
index ddce66d..fa4bed8 100644
--- a/configure.ac
+++ b/configure.ac
@@ -44,7 +44,7 @@ MM_CONFIG_DOCTOOL_DIR([docs])
 AC_SUBST([LIBPANGOMM_SO_VERSION], [1:30:0])
 
 AC_PROG_CXX
-MM_AX_CXX_COMPILE_STDCXX([11], [noext], [mandatory])
+MM_AX_CXX_COMPILE_STDCXX([14], [noext], [mandatory])
 
 AC_DISABLE_STATIC
 LT_INIT([win32-dll])