[NFC]Update a ThinLTO test case (llvm#117584)

Run `function-import` pass in a similar way that it runs in a ThinLTO
distributed backend compile and checks that function alias is imported
as a definition. More accurately, the function alias
[is](https://github.com/llvm/llvm-project/blob/0c98776159cea0d1f391a8e1ac290483d4490240/llvm/lib/Transforms/IPO/FunctionImport.cpp#L1912)
a
[clone](https://github.com/llvm/llvm-project/blob/0c98776159cea0d1f391a8e1ac290483d4490240/llvm/lib/Transforms/IPO/FunctionImport.cpp#L1782)
of the aliasee function.

Author: mingmingl-llvm

llvm/test/ThinLTO/X86/distributed_indexes.ll

@@ -48,6 +48,10 @@
 ; RUN: llvm-dis %t1.bc.thinlto.bc -o - | FileCheck %s --check-prefix=DIS
 ; DIS: aliasee: null
 
+; RUN: opt -passes=function-import -import-all-index -summary-file=%t1.bc.thinlto.bc %t1.bc -S -o - 2>&1 | FileCheck %s --check-prefix=IR
+; Tests that analias definition is imported.
+; IR: define available_externally void @analias
+
 target datalayout = "e-m:o-i64:64-f80:128-n8:16:32:64-S128"
 
 declare void @g(...)