[LV] Add missing REQUIRES: asserts to test using -debug.

Fixup for test added in 5fae408.

Author: fhahn

llvm/test/Transforms/LoopVectorize/uncountable-early-exit-vplan.ll

@@ -1,6 +1,8 @@
 ; NOTE: Assertions have been autogenerated by utils/update_test_checks.py UTC_ARGS: --version 5
 ; RUN: opt -p loop-vectorize -force-vector-width=4 -force-vector-interleave=1 -S -enable-early-exit-vectorization -debug %s 2>&1 | FileCheck %s
 
+; REQUIRES: asserts
+
 declare void @init(ptr)
 
 define i64 @multi_exiting_to_different_exits_live_in_exit_values() {