package/libdrm: fix linking of etnaviv_cmd_stream_test

package/libdrm: fix linking of etnaviv_cmd_stream_test

Fixes
http://autobuild.buildroot.net/results/68a/68af62f4ab6944d326468818562c05fd5cc55b03/
http://autobuild.buildroot.net/results/c33/c3330ef9a8cadb46bbd31c5b14ece34f192133e3/
http://autobuild.buildroot.net/results/d18/d181bd044246646732a14815aae08337b0b5eecf/
http://autobuild.buildroot.net/results/4f5/4f5872211812c7e191cffcf41cab998fc20c0d20/

Signed-off-by: Bernd Kuhls <bernd.kuhls@t-online.de>
[Thomas: add missing autoreconf=yes.]
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>