[gnome-shell-extensions] Add a separate configure option for classic mode datafiles

[Giovanni Campagna <gcampagna src gnome org>]

commit 80b4f108df2c059894bc899b56fef07fec2cf7a4
Author: Giovanni Campagna <gcampagna src gnome org>
Date:   Thu Jan 3 01:21:20 2013 +0100

    Add a separate configure option for classic mode datafiles
    
    Ubuntu wants to install classic mode files but still tweak the set of
    built extensions.
    
    https://bugzilla.gnome.org/show_bug.cgi?id=690799

 configure.ac |   15 ++++++++++++---
 1 files changed, 12 insertions(+), 3 deletions(-)
---
diff --git a/configure.ac b/configure.ac
index c72572a..8dd8fdd 100644
--- a/configure.ac
+++ b/configure.ac
@@ -39,15 +39,24 @@ AC_ARG_ENABLE([extensions],
 	[],
 	[enable_extensions=$DEFAULT_EXTENSIONS]
 )
-AM_CONDITIONAL([CLASSIC_MODE], [test x"$enable_extensions" = xclassic-mode -o x"$enable_extensions" = xall])
 
 if test x"$enable_extensions" = xall; then
    enable_extensions="$ALL_EXTENSIONS"
-fi
-if test x"$enable_extensions" = xclassic-mode; then
+   enable_classic_mode_default=yes
+elif test x"$enable_extensions" = xclassic-mode; then
    enable_extensions="$CLASSIC_EXTENSIONS"
+   enable_classic_mode_default=yes
+else
+   enable_classic_mode_default=no
 fi
 
+AC_ARG_ENABLE([classic-mode],
+        [AS_HELP_STRING([--enable-classic-mode],[Enable installing data files for classic mode.
+        Defaults to yes if enabling all or classic-mode extensions, and no otherwise.])],
+        [],
+        [enable_classic_mode=$enable_classic_mode_default])
+AM_CONDITIONAL([CLASSIC_MODE], [test x"$enable_classic_mode" != xno])
+
 ENABLED_EXTENSIONS=
 for e in $enable_extensions; do
 	case $e in