[root6] Modify StRoot/StBFChain/BFC.C for ROOT6/cling (#423)

StRoot/StBFChain/BFC.C is loaded and executed through the ROOT
interpreter in StBFChain::Setup.

ROOT 6 / cling complains about redefinitions when we run the bfc macro.

Minimal solution is to protect the table implementation for "Bfc" from
being compiled by the cling interpreter (just like it is protected from
compilation by the CINT interpreter).

Likely solves the same problem which Victor was addressing on the Star6
branch.

https://github.com/star-bnl/star-sw/blame/Star6/StRoot/StBFChain/BFC.C#L6

Author: klendathu2k

StRoot/StBFChain/BFC.C

@@ -2,7 +2,7 @@
 #include "TROOT.h"
 #endif
 #include "Bfc.h"
-#if !defined(__CINT__)
+#if !defined(__CINT__) && !defined(__CLING__)
 TableImpl(Bfc);
 #endif
 #include "BigFullChain.h"