examples: build-zlib: Update zlib version to 1.2.11

The previous version is no longer available for download, and this one
builds fine.

Note that the static libraries won't work with the 2.33 compatibility
branch, as they need the extra .o, but the shared ones should be fine.

examples/build-zlib.sh

@@ -1,6 +1,6 @@
 #!/bin/sh
 
-ZLIBVER=1.2.8
+ZLIBVER=1.2.11
 
 # Get the bingcc path: feel free to replace this with a hardcoded path.
 MYFILENAME=`readlink -f "$0"`