Tell glib not to complain about the use of API recently deprecated

When building with glib 2.32 or later, without this #define, it prints a
warning saying:

function "g_value_get_char" was declared deprecated ("Use 'g_value_get_schar' instead")

Since g_value_get_schar is new in 2.32, we can't use it without #ifdef
around the call point. Since the old and new functions are identical in
behavior, just ask glib not to complain about the use of old functions.

I don't know which is the minimum version of glib we require, so I went
for the lowest available macro.

Change-Id: I33f9aa8497fc6bd50fffb3c59ee7e8e7fcdfe110
Reviewed-by: Yoann Lopes <yoann.lopes@digia.com>

src/gsttools/gsttools.pro

@@ -5,6 +5,7 @@ QPRO_PWD = $$PWD
 QT = core-private multimedia-private gui-private
 
 !static:DEFINES += QT_MAKEDLL
+DEFINES += GLIB_VERSION_MIN_REQUIRED=GLIB_VERSION_2_26
 
 unix:!maemo*:contains(QT_CONFIG, alsa) {
 DEFINES += HAVE_ALSA