Fixed for the difference of Cygwin with other Windows variants (MSVC,
Itanium, MinGW).
- The platform name is renamed to "cygwin" from "windows" which is used
for searching the standard libraries.
- The consideration for DLL storage class (DllExport/DllImport) is not
required for Cygwin and MinGW. There is no problem when linking in
these environment.
- Cygwin should use large memory model as default.(This may be changed
if someone ports to 32bit)
- Cygwin and MinGW should use the autolink feature in the sameway of
Linux due to the linker's limit.
