patch 8.0.0674: cannot build with eval but without timers

Problem:    Cannot build with eval but without timers.
Solution:   Add #ifdef (John Marriott)
diff --git a/src/evalfunc.c b/src/evalfunc.c
index 581ad7b..ac232a3 100644
--- a/src/evalfunc.c
+++ b/src/evalfunc.c
@@ -3191,7 +3191,11 @@
 	    ins_typebuf(keys_esc, (remap ? REMAP_YES : REMAP_NONE),
 				  insert ? 0 : typebuf.tb_len, !typed, FALSE);
 	    vim_free(keys_esc);
-	    if (vgetc_busy || timer_busy)
+	    if (vgetc_busy
+#ifdef FEAT_TIMERS
+		    || timer_busy
+#endif
+		    )
 		typebuf_was_filled = TRUE;
 	    if (execute)
 	    {