[glom] Fix the sphinx-build configure check

[David King <davidk src gnome org>]

commit 9b49767af7766c26a03aa4d1377cc833464c1847
Author: David King <davidk openismus com>
Date:   Tue Apr 20 10:16:57 2010 +0200

    Fix the sphinx-build configure check
    
    * configure.ac: Abort configure with an error if sphinx-build could
    not be found and --enable-documentation was passed to configure.

 ChangeLog    |    7 +++++++
 configure.ac |    8 +++++---
 2 files changed, 12 insertions(+), 3 deletions(-)
---
diff --git a/ChangeLog b/ChangeLog
index 9a2f4b4..b3d4204 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,10 @@
+2010-04-20  David King  <davidk openismus com>
+
+	Fix the sphinx-build configure check
+
+	* configure.ac: Abort configure with an error if sphinx-build could
+	not be found and --enable-documentation was passed to configure.
+
 2010-04-20  Murray Cumming  <murrayc murrayc-desktop>
 
 	Glom Python API reference: Failed attempt to dist the html files.
diff --git a/configure.ac b/configure.ac
index 05b44b9..f52b906 100644
--- a/configure.ac
+++ b/configure.ac
@@ -256,10 +256,12 @@ MM_ARG_WITH_TAGFILE_DOC([glibmm-2.4.tag], [glibmm-2.4])
 MM_ARG_WITH_TAGFILE_DOC([cairomm-1.0.tag], [cairomm-1.0])
 MM_ARG_WITH_TAGFILE_DOC([pangomm-1.4.tag], [pangomm-1.4])
 
+AC_ARG_VAR([SPHINX_BUILD], [path to sphinx-build utility])
 AS_IF([test "x$ENABLE_DOCUMENTATION" != xno],
-  [AC_PATH_PROG([SPHINX_BUILD], [sphinx-build], [sphinx-build])],
-  [AC_MSG_ERROR([[The documentation build is enabled, but the sphinx-build tool could not be found.]])]
-)
+  [AC_PATH_PROG([SPHINX_BUILD], [sphinx-build], [sphinx-build])
+   AS_IF([test "x$SPHINX_BUILD" != xsphinx-build],
+     [],
+     [AC_MSG_ERROR([The documentation build is enabled, but the sphinx-build tool could not be found.])])])
 
 AC_CONFIG_FILES([Makefile
                  docs/user-guide/Makefile