Hello I have found a typo in the zlib.h header when it is patched for Qt. Version 4.7.1.

File src/3rdparty/zlib/zlib.h.

Note:
ZEXTERN int ZEXPORT gzungetc OF((int c, gzFile file));

Should be

ZEXTERN int Q_ZEXPORT gzungetc OF((int c, gzFile file));

see below:

ZEXTERN int Q_ZEXPORT gzgetc OF((gzFile file));
/* Reads one byte from the compressed file. gzgetc returns this byte or -1 in case of end of file or error.
*/

ZEXTERN int ZEXPORT gzungetc OF((int c, gzFile file));
/* Push one character back onto the stream to be read again later. Only one character of push-back is allowed. gzungetc() returns the character pushed, or -1 on failure. gzungetc() will fail if a character has been pushed but not read yet, or if c is -1. The pushed character will be discarded if the stream is repositioned with gzseek() or gzrewind().
*/

ZEXTERN int Q_ZEXPORT gzflush OF((gzFile file, int flush));