[gtksourceview] build: remove dead deprecated cflags

[Sébastien Wilmet <swilmet src gnome org>]

commit e2d5110e8fac13fea882dcecfd365c5141636b25
Author: Sébastien Wilmet <swilmet gnome org>
Date:   Sun Jul 12 14:54:45 2015 +0200

    build: remove dead deprecated cflags
    
    Those were useful only for the migration from GNOME/GTK+ 2 to
    GNOME/GTK+ 3. No need to keep them forever.

 configure.ac |    4 +---
 1 files changed, 1 insertions(+), 3 deletions(-)
---
diff --git a/configure.ac b/configure.ac
index 6c50a64..3d8f9ec 100644
--- a/configure.ac
+++ b/configure.ac
@@ -81,9 +81,7 @@ if test "$enable_deprecations" = "no"; then
 -DG_DISABLE_DEPRECATED \
 -DGDK_DISABLE_DEPRECATED \
 -DGTK_DISABLE_DEPRECATED \
--DGDK_PIXBUF_DISABLE_DEPRECATED \
--DGNOME_DISABLE_DEPRECATED \
--DGSEAL_ENABLE"
+-DGDK_PIXBUF_DISABLE_DEPRECATED"
 
        AC_SUBST(DISABLE_DEPRECATED_CFLAGS)
 fi