[folks] Make valadoc a hard dependency when using --enable-docs

[Travis Reitter <treitter src gnome org>]

commit 9b4e626c637ec0f030abc577b4087b5505a35033
Author: Travis Reitter <travis reitter collabora co uk>
Date:   Fri Jun 24 10:04:54 2011 -0700

    Make valadoc a hard dependency when using --enable-docs
    
    Closes: bgo#653325 â Build system does not complain if trying to build docs
    without vala-doc installed

 NEWS         |    2 ++
 configure.ac |    4 ++++
 2 files changed, 6 insertions(+), 0 deletions(-)
---
diff --git a/NEWS b/NEWS
index ac7d486..35c80d0 100644
--- a/NEWS
+++ b/NEWS
@@ -11,6 +11,8 @@ Bugs fixed:
 * Bug 629716 â Migrate Folks to GDBus
 * Bug 652660 â Make Individual.id more stable and well-defined
 * Bug 652449 â Folks.Individual's property getters should be read only
+* Bug 653325 â Build system does not complain if trying to build docs without
+  vala-doc installed
 
 API changes:
 * Swf.Persona retains and exposes its libsocialweb Contact
diff --git a/configure.ac b/configure.ac
index 0a6a0e4..f8145b2 100644
--- a/configure.ac
+++ b/configure.ac
@@ -323,6 +323,10 @@ AS_IF([test "x$enable_docs" != xno],
        AS_IF([test "$VALADOC" != :], have_valadoc=yes)])
 AM_CONDITIONAL([HAVE_VALADOC], [test x$have_valadoc = xyes])
 
+if test "x$enable_docs" = "xyes" -a "x$have_valadoc" != "xyes"; then
+    AC_MSG_ERROR([Doc building requested but valadoc not installed.])
+fi
+
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