This fixes a bug where 64 bit builds with /bigobj incorrectly determined
that the object files were not 64 bit. This manifested itself with
printf type functions showing up as undefined because the leading
underscore was being removed and should not be removed.
Create target property WINDOWS_EXPORT_ALL_SYMBOLS to automatically
generate a module definition file from MS-compatible .obj files and give
it to the linker in order to export all symbols from the .dll part of a
SHARED library.