[UnitTest] Fix warning, NFC.

Use an unsigned literal to avoid signedness mismatch in the compare.

llvm-svn: 257747
diff --git a/llvm/unittests/IR/InstructionsTest.cpp b/llvm/unittests/IR/InstructionsTest.cpp
index afcccb3..53c3847 100644
--- a/llvm/unittests/IR/InstructionsTest.cpp
+++ b/llvm/unittests/IR/InstructionsTest.cpp
@@ -541,7 +541,7 @@
   EXPECT_EQ(Call->getTailCallKind(), Clone->getTailCallKind());
   EXPECT_TRUE(Clone->hasFnAttr(Attribute::AttrKind::Cold));
   EXPECT_EQ(Call->getDebugLoc(), Clone->getDebugLoc());
-  EXPECT_EQ(Clone->getNumOperandBundles(), 1);
+  EXPECT_EQ(Clone->getNumOperandBundles(), 1U);
   EXPECT_TRUE(Clone->getOperandBundle("after").hasValue());
 }