apply windows patch separately

we apply it with `--binary` option to allow Windows line endings
setting patch type *.diff_bin to binary via .gitattributes

.gitattributes

@@ -2,4 +2,5 @@
 * text=auto eol=lf
 # except for Windows batch files
 *.{cmd,[cC][mM][dD]} text eol=crlf
-*.{bat,[bB][aA][tT]} text eol=crlf
+*.{bat,[bB][aA][tT]} text eol=crlf
+*.diff_bin binary

build/pkgs/zlib/patches/cygwin-gzopen_w.patch

@@ -1,10 +1,7 @@
-Patch needed for zlib to build on Cygwin.  This is needed due to a misguided
-and broken attempt to add unnecessary wide character interfaces on Cygwin
-(which generally works more on the POSIX philosophy for filenames).
-See https://trac.sagemath.org/ticket/23083
-diff -ruN a/gzguts.h b/gzguts.h
---- a/gzguts.h	2017-05-26 12:14:03.500413900 +0200
-+++ b/gzguts.h	2017-05-26 12:14:28.200295200 +0200
+diff --git a/gzguts.h b/gzguts.h
+index 990a4d2..6378d46 100644
+--- a/gzguts.h
++++ b/gzguts.h
 @@ -39,7 +39,7 @@
  #  include <io.h>
  #endif
@@ -14,11 +11,3 @@ diff -ruN a/gzguts.h b/gzguts.h
  #  define WIDECHAR
  #endif
 
-diff -ruN a/win32/zlib.def b/win32/zlib.def
---- a/win32/zlib.def	2017-05-26 12:14:03.744912800 +0200
-+++ b/win32/zlib.def	2017-05-26 12:15:02.512250800 +0200
-@@ -91,4 +91,3 @@
-     inflateCodesUsed
-     inflateResetKeep
-     deflateResetKeep
--    gzopen_w

build/pkgs/zlib/patches/cygwin-windef.diff_bin

@@ -0,0 +1,9 @@
+diff --git a/win32/zlib.def b/win32/zlib.def
+index 784b138..b69fa3e 100644
+--- a/win32/zlib.def
++++ b/win32/zlib.def
+@@ -91,4 +91,3 @@ EXPORTS
+     inflateCodesUsed
+     inflateResetKeep
+     deflateResetKeep
+-    gzopen_w

build/pkgs/zlib/spkg-install.in

@@ -1,5 +1,6 @@
 cd src/
-
+echo "patching win32/zlib.def with a binary patch"
+patch -p1 --posix --binary <"$SAGE_ROOT/build/pkgs/zlib/patches/cygwin-windef.diff_bin"
 
 if [ "$UNAME" = CYGWIN ]; then
     export BINARY_PATH="$SAGE_LOCAL/bin"