bufferpool: Update the configure even if set_config() returned false
bufferpool: Update the configure even if set_config() returned false

According to the documentation, when set_config() return false, it should be
possible to read the modified version of the config. This patch fixes the
implementation so it is now according to the documentation.

https://bugzilla.gnome.org/show_bug.cgi?id=727916

surround-io/gstreamer,krichter722/gstreamer,shelsonjava/gstreamer,jpxiong/gstreamer,Lachann/gstreamer,StreamUtils/gstreamer,shelsonjava/gstreamer,mparis/gstreamer,Lachann/gstreamer,surround-io/gstreamer,jpakkane/gstreamer,krichter722/gstreamer,surround-io/gstreamer,jpakkane/gstreamer,surround-io/gstreamer,krichter722/gstreamer,Lachann/gstreamer,shelsonjava/gstreamer,Lachann/gstreamer,krichter722/gstreamer,StreamUtils/gstreamer,jpxiong/gstreamer,StreamUtils/gstreamer,jpakkane/gstreamer,jpxiong/gstreamer,jpxiong/gstreamer,jpakkane/gstreamer,centricular/gstreamer,shelsonjava/gstreamer,centricular/gstreamer,jpxiong/gstreamer,mparis/gstreamer,mparis/gstreamer,centricular/gstreamer,mparis/gstreamer,jpakkane/gstreamer,shelsonjava/gstreamer,surround-io/gstreamer,StreamUtils/gstreamer,centricular/gstreamer,StreamUtils/gstreamer,centricular/gstreamer,krichter722/gstreamer,mparis/gstreamer,Lachann/gstreamer