Windows: rm BA_CORE_API and WinDll.h fromm Fit

Core/Parametrization/RealParameter.h

Fit/Kernel/FitOptions.h

Fit/Kernel/IFunctionAdapter.h

Fit/Kernel/Kernel.h

Fit/Kernel/Minimizer.h

Fit/Kernel/MinimizerResult.h

Fit/Kernel/Parameter.h

Fit/Kernel/Parameters.h

Fit/Kernel/PyCallback.h

Fit/Minimizer/IMinimizer.h

Fit/Minimizer/MinimizerCatalog.h

Fit/Minimizer/MinimizerFactory.h

Fit/Minimizer/MinimizerInfo.h

Fit/Minimizer/MinimizerOptions.h

Fit/Minimizer/TestMinimizer.h

Fit/RootAdapter/GSLLevenbergMarquardtMinimizer.h

Fit/RootAdapter/GSLMultiMinimizer.h

Fit/RootAdapter/GeneticMinimizer.h

Fit/RootAdapter/MinimizerResultUtils.h

Fit/RootAdapter/Minuit2Minimizer.h