gzip -d with zcat enabled but gunzip disabled was misbehaving

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
diff --git a/archival/bbunzip.c b/archival/bbunzip.c
index 87a8022..6244bce 100644
--- a/archival/bbunzip.c
+++ b/archival/bbunzip.c
@@ -386,7 +386,7 @@
 	 * Normally, "zcat" is just "gunzip -c".
 	 * But if seamless magic is enabled, then we are much more clever.
 	 */
-	if (ENABLE_ZCAT && (!ENABLE_GUNZIP || applet_name[1] == 'c'))
+	if (ENABLE_ZCAT && applet_name[1] == 'c')
 		option_mask32 |= BBUNPK_OPT_STDOUT | BBUNPK_SEAMLESS_MAGIC;
 
 	return bbunpack(argv, unpack_gz_stream, make_new_name_gunzip, /*unused:*/ NULL);