[glom] configure.ac: Fail if we can't find boost-python.

[Murray Cumming <murrayc src gnome org>]

commit e0a508c1206663e311df36aa11947f2b236c01a7
Author: Murray Cumming <murrayc murrayc com>
Date:   Fri Apr 25 09:38:16 2014 +0200

    configure.ac: Fail if we can't find boost-python.

 configure.ac |    4 ++++
 1 files changed, 4 insertions(+), 0 deletions(-)
---
diff --git a/configure.ac b/configure.ac
index f0bf933..b5cf16a 100644
--- a/configure.ac
+++ b/configure.ac
@@ -247,6 +247,10 @@ AX_BOOST_BASE
 # See http://www.gnu.org/software/autoconf-archive/ax_boost_python.html
 AX_BOOST_PYTHON
 
+# Check that ax_boost_python.m4 found something.
+# It also defines HAVE_BOOST_PYTHON, but only as a C define for 
+AS_IF([test -z "$BOOST_PYTHON_LIB"],
+  [AC_MSG_ERROR([Cannot find the Boost::Python library.])])
 
 AC_ARG_ENABLE([update-mime-database],
               [AS_HELP_STRING([--disable-update-mime-database],