[llvm] [SystemZ] Add missing (dis-)assembly tests. (PR #88498)

[Ulrich Weigand via llvm-commits]

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@@ -989,6 +995,9 @@
 # CHECK: vflcsb %v14, %v17
 0xe7 0xe1 0x00 0x00 0x24 0xcc
 
+# CHECK: vflls %v0, %v1
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uweigand wrote:

Also, shouldn't we then also test the wffls variant?

https://github.com/llvm/llvm-project/pull/88498