Include the Encode extension in the ALL_STATIC build on Win32 for VC++

Include the Encode extension in the ALL_STATIC build on Win32 for VC++

Thanks to Jan Dubois and Nicholas Clark for pointing out that Encode has
subextensions which need statically linking too, and that Configure has
a special case for handling this which we can mimic in config_sh.PL.

Unfortunately, however, while this works for VC++, with MinGW it gives
undefined reference errors to three symbols from Encode/CN.o
(_cp936_encoding, _euc_cn_encoding and MacChineseSimp_encoding) and two
from Encode/JP.o (_cp932_encoding and _euc_jp_encoding), so we must retain
the exclusion on Encode for MinGW for now, much like the Compress/Raw/Bzip2
problem found before. Hopefully these are all fixable soon.