[gnome-online-accounts] build: Fix Kerberos never being automatically enabled

[Bastien Nocera <hadess src gnome org>]

commit f8f1e79887d26530755f022e5b5e5af7222cb186
Author: Bastien Nocera <hadess hadess net>
Date:   Tue Jul 4 14:27:46 2017 +0200

    build: Fix Kerberos never being automatically enabled
    
    Kerberos support was never enabled even if the support libraries were
    detected on the system because the wrong variable was set. We also want
    to make sure that Kerberos detection is attempted even if not requested,
    and error out only if requested but not available.
    
    We also need to make sure that "gcr" is checked for early, to avoid
    kerberos being marked as available when a support library is missing.
    
    https://bugzilla.gnome.org/show_bug.cgi?id=784513

 configure.ac |   14 +++++++++-----
 1 files changed, 9 insertions(+), 5 deletions(-)
---
diff --git a/configure.ac b/configure.ac
index 6bc0061..439555c 100644
--- a/configure.ac
+++ b/configure.ac
@@ -381,14 +381,14 @@ fi
 AC_DEFINE(GOA_KERBEROS_NAME, ["kerberos"], [ProviderType and extension point name])
 AC_ARG_ENABLE([kerberos],
               [AS_HELP_STRING([--enable-kerberos], [Enable kerberos support])],
-              [with_kerberos=$enableval],
-              [enable_kerberos=no])
+              [enable_kerberos=$enableval],
+              [enable_kerberos=auto])
 AC_PATH_PROG([KRB5_CONFIG], krb5-config, none, $PATH:/usr/kerberos/bin)
 
 if test "x$KRB5_CONFIG" != "xnone"; then
     KRB5_LIBS="`${KRB5_CONFIG} --libs krb5`"
     KRB5_CFLAGS="`${KRB5_CONFIG} --cflags krb5`"
-    have_kerberos=yes
+    PKG_CHECK_MODULES(GCR, gcr-3, [have_kerberos=yes], [have_kerberos=no])
 else
     KRB5_LIBS=""
     KRB5_CFLAGS=""
@@ -398,13 +398,17 @@ AC_SUBST(KRB5_CFLAGS)
 AC_SUBST(KRB5_LIBS)
 
 if test "$enable_kerberos" != "no"; then
-  if test "$have_kerberos" = "no" ; then
+  if test "$enable_kerberos" == "yes" &&
+     test "$have_kerberos" == "no" ; then
       AC_MSG_ERROR([kerberos support requested, but not available])
   fi
 
-  PKG_CHECK_MODULES(GCR, gcr-3)
+  enable_kerberos=$have_kerberos
+
   AC_DEFINE(GCR_API_SUBJECT_TO_CHANGE, 1, [Define to use the GCR API])
   AC_DEFINE(GOA_KERBEROS_ENABLED, 1, [Enable Enterprise Identity data provider])
+else
+  enable_kerberos=no
 fi
 AM_CONDITIONAL(BUILD_KERBEROS, [test x$enable_kerberos != xno])