[llvm] [NFC]Make file-local cl::opt global variables static (PR #126486)

[Matt Arsenault via llvm-commits]

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@@ -17,16 +17,16 @@
 using namespace llvm;
 namespace llvm::sandboxir {
 
-cl::opt<unsigned> SeedBundleSizeLimit(
+static cl::opt<unsigned> SeedBundleSizeLimit(
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arsenm wrote:

These are under the namespace but it doesn't really matter 

https://github.com/llvm/llvm-project/pull/126486