#196 Current master branch failed to build on ubuntu 20.04

[Xiao Hanyu]

Hello,

It seems that the current master branch of xetex failed to build on ubuntu 20.04.

Steps to reproduce:
- Grab a virtual machine box from: https://www.osboxes.org/ubuntu/#ubuntu-20-04-4-vmware
- Get the code
- set up the environment:
- sudo apt install build-essential pkg-config autoconf libtool
- sudo apt install libfontconfig1-dev
- execute build.sh and it will reports some error (please check the attached file for detailed log):

cc1: warning: unrecognized command line option ‘-Wno-parentheses-equality’
  CCLD     ctangle
  CTANGLE  tie.c
  CC       tie-tie.o
../../../source/texk/web2c/tiedir/tie-w2c.ch: In function ‘main’:
../../../source/texk/web2c/tiedir/tie-w2c.ch:151:1: warning: format not a string literal and no format arguments [-Wformat-security]
  151 |   print_ln(versionstring);  /* Web2C version */
      | ^ ~~~~~~
../../../source/texk/web2c/tiedir/tie.w: At top level:
cc1: warning: unrecognized command line option ‘-Wno-parentheses-equality’
  CCLD     tie
  TIE      xetex.ch
  OTANGLE  xetex
  WEB2C    xetex
syntax error: Last token = 59 (;), error buffer = `;',
        last id = `gzFile' (not in symbol table).
./web2c/splitup: fatal: No #include xetexcoerce.h line.
../../../source/texk/web2c/web2c/convert: conversion of xetex.p failed, moving dregs:
../../../source/texk/web2c/web2c/convert:   mv xetex[0-9].c xetexini.c xetexd.h                   xetexcoerce.h /tmp
mv: cannot stat 'xetex[0-9].c': No such file or directory
mv: cannot stat 'xetexini.c': No such file or directory
make: *** [Makefile:17308: xetex-web2c] Error 1
make: Leaving directory '/home/osboxes/work/xetex-code4/build/texk/web2c'

After some investigation I found the problematic commit, specifically, this line leads to the build failure, i.e, removing of @define type gzFile; lead to the failed build, which also matches the error log: last id = 'gzFile' (not in symbol table).

I can provide a patch if this looks good.