Revert r165777, "Mark function as 'used' so that LTO doesn't try to get rid of it."

llvm-svn: 165780
diff --git a/llvm/unittests/ExecutionEngine/JIT/JITTest.cpp b/llvm/unittests/ExecutionEngine/JIT/JITTest.cpp
index 1eff4d6..5e2af03 100644
--- a/llvm/unittests/ExecutionEngine/JIT/JITTest.cpp
+++ b/llvm/unittests/ExecutionEngine/JIT/JITTest.cpp
@@ -633,7 +633,7 @@
 // This function is intentionally defined differently in the statically-compiled
 // program from the IR input to the JIT to assert that the JIT doesn't use its
 // definition.
-extern "C" int32_t JITTest_AvailableExternallyFunction() __attribute__((used)) {
+extern "C" int32_t JITTest_AvailableExternallyFunction() {
   return 42;
 }
 namespace {