missing export from native msvcrt

[Ann and Jason Edmeades]

> From attempting to run pgm with native msvcrt, w2k scrrun.dll:

fixme:win32:PE_CreateModule Security directory ignored
err:win32:PE_FindExportedFunction function not found for forward
'ntdll._iswalpha' used by 'msvcrt.dll'. If you are using builtin
'msvcrt.dll', try using the native one instead.
err:win32:PE_fixup_imports No implementation for MSVCRT.DLL.636(iswalpha)
imported from F:\badcomp\windlls\scrrun.dll, setting to 0xdeadbeef

Raised as bug#730

Regards,
Jason