package/lttng-tools: needs dynamic library support

Fixes:
  http://autobuild.buildroot.net/results/b48bc7ad4bede4d16c079da0ae1121e6796a0e8d/
  http://autobuild.buildroot.net/results/25dcb19c3dd32e50990f9b45053d71ea18746a80/
  http://autobuild.buildroot.net/results/a3f93498811491d37ba13d024e33e68a8bc7ba18/



Signed-off-by: Samuel Martin <s.martin49@gmail.com>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>