Various changes to make this stuff compile under Win32 and VC++ with and

Various changes to make this stuff compile under Win32 and VC++ with and
without -debug option to mk1mf.pl. Change _export to is_export (_export is
a reserved word under VC++). Add yucky function prototype function pointer
casts. Sanitise the included files in crypto/x509v3.

Also changed ssleay.exe target to openssl.exe