[gcalctool] Drop support for GTK2

[Robert Ancell <rancell src gnome org>]

commit f263704e1d79f409d104eb1c17d1b55e6949c3ae
Author: Robert Ancell <robert ancell canonical com>
Date:   Thu May 26 15:58:45 2011 +1000

    Drop support for GTK2

 NEWS         |    1 +
 configure.ac |   22 ++--------------------
 2 files changed, 3 insertions(+), 20 deletions(-)
---
diff --git a/NEWS b/NEWS
index 323aa88..6702eac 100644
--- a/NEWS
+++ b/NEWS
@@ -18,6 +18,7 @@ Overview of changes in gcalctool 6.1.0
     * Fix thousands separator being on front of three digit numbers
     * Don't clear display when entering digit inside result
     * Add a swap units button (Jonh Wendell, Bug #633193)
+    * Drop support for GTK2
 
 Overview of changes in gcalctool 6.0.0
 
diff --git a/configure.ac b/configure.ac
index fea10c6..11f95f8 100644
--- a/configure.ac
+++ b/configure.ac
@@ -20,28 +20,10 @@ dnl Dependencies
 dnl ###########################################################################
 
 GIO_REQUIRED=2.25.10
-
-AC_MSG_CHECKING([which gtk+ version to compile against])
-AC_ARG_WITH([gtk],
-  [AS_HELP_STRING([--with-gtk=2.0|3.0],[which gtk+ version to compile against (default: 3.0)])],
-  [case "$with_gtk" in
-     2.0|3.0) ;;
-     *) AC_MSG_ERROR([invalid gtk version specified]) ;;
-   esac],
-  [with_gtk=3.0])
-AC_MSG_RESULT([$with_gtk])
-
-case "$with_gtk" in
-  2.0) GTK_API_VERSION=2.0
-       GTK_REQUIRED=2.21.8
-       ;;
-  3.0) GTK_API_VERSION=3.0
-       GTK_REQUIRED=2.90.7
-       ;;
-esac
+GTK_REQUIRED=2.90.7
 
 PKG_CHECK_MODULES(GCALCTOOL, [
-    gtk+-$GTK_API_VERSION >= $GTK_REQUIRED
+    gtk+-3.0 $GTK_REQUIRED
     gio-2.0 >= $GIO_REQUIRED
     libxml-2.0
     gmodule-export-2.0