Missing line in patch

Sorry... that patch I sent was missing a line (the prototype of a
function). Here is the complete one.

/* Prototype copied from below so we can use it in SgExpression::symbol(). */
SgValueExp *             isSgValueExp(SgExpression *pt);

inline SgSymbol *SgExpression::symbol()
     /* Value expressions do not have valid symbol pointers */
     if ( isSgValueExp (this) )
          return 0;
          return SymbMapping(NODE_SYMB(thellnd));