[gdk-pixbuf] configure: add an option to deactivate gio sniffing

[Lionel Landwerlin <llandwerlin src gnome org>]

commit cf4dc4cabdeffbc32a6e2216a099e1e3039d9d9c
Author: Lionel Landwerlin <llandwerlin gmail com>
Date:   Thu May 24 10:54:36 2012 +0100

    configure: add an option to deactivate gio sniffing
    
    At the moment gio sniffing support is detected at configure time by
    compiling a piece of C code and running it. This obviously can't work
    when cross compiling.
    
    This patch adds an option to force gio sniffing enabling/disabling at
    configure time but still keeps the previous behavior when no hint is
    given.
    
    https://bugzilla.gnome.org/show_bug.cgi?id=676726

 configure.ac |   14 +++++++++++++-
 1 files changed, 13 insertions(+), 1 deletions(-)
---
diff --git a/configure.ac b/configure.ac
index 00d977f..73f5bf1 100644
--- a/configure.ac
+++ b/configure.ac
@@ -95,6 +95,11 @@ PKG_PROG_PKG_CONFIG
 
 AC_CANONICAL_HOST
 
+AC_ARG_ENABLE(gio-sniffing,
+              [AC_HELP_STRING([--enable-gio-sniffing=@<:@no/yes/auto@:>@],
+                              [enable or disable gio sniffing [default=auto]])],,
+              [enable_gio_sniffing=auto])
+
 MATH_LIB=-lm
 AC_MSG_CHECKING([for native Win32])
 LIB_EXE_MACHINE_FLAG=X86
@@ -746,7 +751,7 @@ AM_CONDITIONAL(INCLUDE_QTIF, [test x"$INCLUDE_qtif" = xyes])
 # check one of the variables here
 AM_CONDITIONAL(INCLUDE_GDIPLUS, [test x"$INCLUDE_gdip_ico" = xyes])
 
-if test x$gio_can_sniff = x; then
+if test x$enable_gio_sniffing = xauto && test x$gio_can_sniff = x; then
   AC_MSG_CHECKING([if gio can sniff png])
   gtk_save_LIBS="$LIBS"
   gtk_save_CFLAGS="$CFLAGS"
@@ -788,6 +793,13 @@ if test x$gio_can_sniff = x; then
   AC_MSG_RESULT($gio_can_sniff)
   LIBS="$gtk_save_LIBS"
   CFLAGS="$gtk_save_CFLAGS"
+else
+  if test x$enable_gio_sniffing = xyes; then
+     gio_can_sniff=yes
+     AC_DEFINE(GDK_PIXBUF_USE_GIO_MIME, 1, [Define if gio can sniff image data])
+  else
+     gio_can_sniff=no
+  fi
 fi
 
 AM_CONDITIONAL(HAVE_TIFF, test "x$LIBTIFF" != x)