Modify THcFormula to properly handle kCutScaler and kCutNCalled.

This is a temporary fix for problem that arise when compiling on the
ifarm machines. In the DefinedValue method when using
kCutScaler and kCutNCalled the switch statement goes to the default
case.

On ifarm gcc version 4.4.6 20110731 (Red Hat 4.4.6-3) (GCC)
There are compiler warnings
 src/THcFormula.cxx: In member function 'virtual Double_t THcFormula::DefinedValue(Int_t)':
src/THcFormula.cxx:131: warning: case label value exceeds maximum value for type
src/THcFormula.cxx:134: warning: case label value exceeds maximum value for type
One permenant fix would be to add kCutScaler and kCutNCalled to the
enum EVariableType in THaFormula.h.

src/THcFormula.cxx

@@ -121,7 +121,7 @@ Double_t THcFormula::DefinedValue( Int_t i )
   FVarDef_t* def = fVarDef+i;
   const void* ptr = def->code;
   if( !ptr ) return kBig;
-  switch( def->type ) {
+  switch( (Int_t) def->type ) {
   case kVariable:
   case kString:
     return reinterpret_cast<const THaVar*>(ptr)->GetValue( def->index );