In order to support `gzip' encoded header the call to
`inflateInit2' was modified in commit 6a92b1fadd.
However, this code breaks with the outdated internal version
of zlib. This is a temporary fix to conditionally support
`gzip' encoded header whenever a system installation of zlib
is being used.
Problem report in
https://lists.nongnu.org/archive/html/freetype-devel/2020-02/msg00023.html
* src/gzip/ftgzip.c (FT_Gzip_Uncompress): Change the the call to
`inflateInit2' depending on whether the system installation is
being used or the internal copy.