Two more README.MinGW specific comments

[Tom Koelman]

First a very minor one:
- The location of zlib is
http://prdownloads.sourceforge.net/gnuwin32/zlib-1.1.4-lib.zip
  the one in README.MinGW contains two typos.

Second: 
Foundation doesn't work very well when iconv is not installed. The
README says iconv is optional, but I think that either it isn't, or
foundation contains a bug. When iconv isn't installed, GSToUnicode
will return NO when converting a string from an encoding other than a
certain list of encodings among which is not NSUTF8StringEncoding.
NSDictionary's writeToFile, which converts a NSDictionary to a
propertylist, which it tries to convert to the encoding
NSUTF8StringEncoding, will consequently not write anything at all and
fail silently.

I suggest changing README.MinGW as follows:

make.patch
Description: Text Data

Tom