gz_open and gz_close were left in, even when BB_FEATURE_TAR_GZIP was disabled.
Fix that.
diff --git a/gunzip.c b/gunzip.c
index 1107bc7..51541f1 100644
--- a/gunzip.c
+++ b/gunzip.c
@@ -1017,6 +1017,7 @@
 	return 0;
 }
 
+#ifdef BB_FEATURE_TAR_GZIP
 extern int gz_open(FILE *compressed_file, int *pid)
 {
 	int unzip_pipe[2];
@@ -1056,6 +1057,7 @@
 	free(window);
 	free(crc_table);
 }
+#endif	
 
 extern int gunzip_main(int argc, char **argv)
 {