Fix Fedora 26 test failure

On Fedora 26 when gr-gsm is installed in /usr/local/lib in order to work
some paths have to be added to PYTHONPATH and LD_LIBRARY_PATH enviroment
variables

This fixes the following errors
    ImportError: No module named grgsm
    ImportError: No module named _grgsm_swig
    ImportError: libgrgsm-0.41.3.so.0.0.0: cannot open shared object file: No such file or directory
diff --git a/tests/scripts/decode.sh b/tests/scripts/decode.sh
index 3fb90ff..c71b26e 100755
--- a/tests/scripts/decode.sh
+++ b/tests/scripts/decode.sh
@@ -2,6 +2,10 @@
 
 TEST_DIR=`dirname "$0"`
 
+# PYTHONPATH and LD_LIBRARY_PATH are needed on Fedora 26
+export PYTHONPATH=/usr/local/lib64/python2.7/site-packages/:/usr/local/lib64/python2.7/site-packages/grgsm/:$PYTHONPATH
+export LD_LIBRARY_PATH=/usr/local/lib64/:$LD_LIBRARY_PATH
+
 export AP_DECODE="grgsm_decode"
 export CAPFILE="../../test_data/vf_call6_a725_d174_g5_Kc1EF00BAB3BAC7002.cfile"
 export SHORTENED_CAPFILE="tmp.cfile"