package/linphone: needs speexdsp

Fixes
http://autobuild.buildroot.net/results/956/956b8cffa0a35a417763ad72bb7c8e8a8b2fe6b0/

Signed-off-by: Bernd Kuhls <bernd.kuhls@t-online.de>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@bootlin.com>

package/linphone/Config.in

@@ -5,6 +5,7 @@ config BR2_PACKAGE_LINPHONE
 	depends on BR2_USE_MMU # libeXosip2
 	select BR2_PACKAGE_LIBEXOSIP2
 	select BR2_PACKAGE_SPEEX
+	select BR2_PACKAGE_SPEEXDSP
 	help
 	  Linphone is an internet phone or Voice Over IP phone (VoIP).