Makefile: Also remove old versions of libiio
Makefile: Also remove old versions of libiio

Otherwise they will cause a build failure when building the test
programs.

Signed-off-by: Paul Cercueil <73d292422978d45c9eeef455bb1b24a0db453722@analog.com>

sensarliar/libiio,analogdevicesinc/libiio,Sunderfield/libiio,analogdevicesinc/libiio,sensarliar/libiio,analogdevicesinc/libiio,Sunderfield/libiio,gburca/libiio,gburca/libiio,sensarliar/libiio,Sunderfield/libiio,gburca/libiio,analogdevicesinc/libiio