Update zconf.h and gzio.c with changes from ZLib 1.2.1 to ZLib 1.2.2.

These are two of the three files that have non-trivial differences from
the vendor branch.  minigzip.c is the third, but there were no changes
from ZLib 1.2.1 to ZLib 1.2.2 in that file.

The rest of the files I intend to get reverted back to the vendor
branch (with cooperation of cvsadmin@).

PR:		i386/76294

1 files changed, 4 insertions, 0 deletions

diff --git a/lib/libz/gzio.c b/lib/libz/gzio.c
index 88e3f03..5424de0 100644
--- a/lib/libz/gzio.c
+++ b/lib/libz/gzio.c
@@ -456,6 +456,10 @@ int ZEXPORT gzread (file, buf, len)
                     s->z_err = Z_ERRNO;
                     break;
                 }
+                if (feof(s->file)) {        /* avoid error for empty file */
+                    s->z_err = Z_STREAM_END;
+                    break;
+                }
             }
             s->stream.next_in = s->inbuf;
         }