jenkins-build-srslte.sh: allow custom binaries

this allows to specify the environmental var
wanted_binaries_bin that will be included in the
trial package. if the variable isn't set, all three
main srsLTE binaries are included

Change-Id: I63f5799328435ce32b5bfd6dae6fd0b37e1e5397
diff --git a/contrib/jenkins-build-srslte.sh b/contrib/jenkins-build-srslte.sh
index 80e4ffc..365c3e4 100755
--- a/contrib/jenkins-build-srslte.sh
+++ b/contrib/jenkins-build-srslte.sh
@@ -1,6 +1,10 @@
 #!/bin/sh
 set -e -x
 
+if [ -z "$trial_binaries" ]; then
+  trial_binaries="srsue srsenb srsepc"
+fi
+
 base="$PWD"
 name="srslte"
 git_url="${git_url:-https://github.com/srsLTE}"
@@ -10,4 +14,4 @@
 #TODO: make sure libconfig, zeroMQ is installed
 build_repo $project_name $configure_opts
 
-create_bin_tgz "srsue srsenb srsepc"
+create_bin_tgz "$trial_binaries"