Remove configure check for z_streamp

This is surely obsolete.  zlib version 1.0.4, which includes
z_streamp, was released 1996-07-24.  When this check was put in in
2001 (19c97b8579), the commit was already labeling that release as
ancient.

Reviewed-by: Tristan Partin <tristan@neon.tech>
Discussion: https://www.postgresql.org/message-id/flat/33462926-bb1e-7cc9-8d92-d86318e8ed1d%40eisentraut.org

configure

@@ -15162,21 +15162,6 @@ _ACEOF
 fi
 
 
-if test "$with_zlib" = yes; then
-  # Check that <zlib.h> defines z_streamp (versions before about 1.0.4
-  # did not).  While we could work around the lack of z_streamp, it
-  # seems unwise to encourage people to use such old zlib versions...
-  ac_fn_c_check_type "$LINENO" "z_streamp" "ac_cv_type_z_streamp" "#include <zlib.h>
-"
-if test "x$ac_cv_type_z_streamp" = xyes; then :
-
-else
-  as_fn_error $? "zlib version is too old
-Use --without-zlib to disable zlib support." "$LINENO" 5
-fi
-
-fi
-
 case $host_cpu in
   x86_64)
     # On x86_64, check if we can compile a popcntq instruction

configure.ac

@@ -1678,15 +1678,6 @@ AC_CHECK_TYPES([struct option], [], [],
 #include <getopt.h>
 #endif])
 
-if test "$with_zlib" = yes; then
-  # Check that <zlib.h> defines z_streamp (versions before about 1.0.4
-  # did not).  While we could work around the lack of z_streamp, it
-  # seems unwise to encourage people to use such old zlib versions...
-  AC_CHECK_TYPE(z_streamp, [], [AC_MSG_ERROR([zlib version is too old
-Use --without-zlib to disable zlib support.])],
-                [#include <zlib.h>])
-fi
-
 case $host_cpu in
   x86_64)
     # On x86_64, check if we can compile a popcntq instruction

meson.build

@@ -1384,14 +1384,6 @@ if not zlibopt.disabled()
       args: test_c_args, include_directories: postgres_inc,
       dependencies: [zlib_t], required: zlibopt)
     warning('zlib header not found')
-  elif not cc.has_type('z_streamp',
-      dependencies: [zlib_t], prefix: '#include <zlib.h>',
-      args: test_c_args, include_directories: postgres_inc)
-    if zlibopt.enabled()
-      error('zlib version is too old')
-    else
-      warning('zlib version is too old')
-    endif
   else
     zlib = zlib_t
   endif