make xrootd to find the proper libXrdSec shared library instead of setting a fixed version

Author: Diego Davila

osgtest/tests/test_150_xrootd.py

@@ -7,7 +7,7 @@
 
 XROOTD_CFG_TEXT = """\
 cms.space min 2g 5g
-xrootd.seclib /usr/lib64/libXrdSec-4.so
+xrootd.seclib libXrdSec.so
 sec.protocol /usr/lib64 gsi -certdir:/etc/grid-security/certificates \
     -cert:/etc/grid-security/xrd/xrdcert.pem \
     -key:/etc/grid-security/xrd/xrdkey.pem \