[Bug bootstrap/79771] [7 Regression] in-tree zlib breaks build

[yselkowi at redhat dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=79771

--- Comment #4 from Yaakov Selkowitz <yselkowi at redhat dot com> ---
This is an upstream issue in the recent zlib releases, here's a patch:

https://github.com/cygwinports/zlib/blob/master/1.2.11-gzopen_w.patch

Configuring with --with-system-zlib avoids this, as long as gcc doesn`t try
using the Win32-only gzopen_w on Cygwin (which it hasn't in the past).