patch ABC to parse "^" in XAG

abc.patch

diff --git a/src/base/io/ioReadEqn.c b/src/base/io/ioReadEqn.c
index 1e4f5d46..e3349ed4 100644
--- a/src/base/io/ioReadEqn.c
+++ b/src/base/io/ioReadEqn.c
@@ -154,7 +154,7 @@ Abc_Ntk_t * Io_ReadEqnNetwork( Extra_FileReader_t * p )
                 // make a copy of formula for names
                 pFormulaCopy = Extra_UtilStrsav( pFormula );
                 // find the names of the fanins of this node
-                Io_ReadEqnStrCutAt( pFormulaCopy, "!*+()", 1, vVars );
+                Io_ReadEqnStrCutAt( pFormulaCopy, "!*^+()", 1, vVars );
             }
             // create the node
             pNode = Io_ReadCreateNode( pNtk, pNodeName, (char **)Vec_PtrArray(vVars), Vec_PtrSize(vVars) );