[gimp/gtk3-port: 250/457] configure.ac: don't define GDK/GTK_MULTIHEAD_SAFE, they are gone

[Michael Natterer <mitch src gnome org>]

commit c20318a5526f9a257158814c98479b1fe703d3c5
Author: Michael Natterer <mitch gimp org>
Date:   Sun Apr 29 03:53:56 2018 +0200

    configure.ac: don't define GDK/GTK_MULTIHEAD_SAFE, they are gone

 configure.ac |    7 -------
 1 files changed, 0 insertions(+), 7 deletions(-)
---
diff --git a/configure.ac b/configure.ac
index bcfc468..ac6c01a 100644
--- a/configure.ac
+++ b/configure.ac
@@ -2450,13 +2450,6 @@ if test "x$have_pango_1_32" != "xyes"; then
 fi
 
 
-############################
-# Require multihead safe API
-############################
-
-CPPFLAGS="${CPPFLAGS} -DGDK_MULTIHEAD_SAFE -DGTK_MULTIHEAD_SAFE"
-
-
 ##################
 # configure output
 ##################