vold: Use Wakelock::tryGet()

Acquiring a wakelock can fail if the suspend service is unavailable.
Explicitly check that wakelock was acquired before performing
operations that require the device to stay on.

Bug: b/179229598
Test: Boot test on Pixel 4 device
Change-Id: If30087223e44098801a31d1bfd239ac22e891abe
diff --git a/Benchmark.cpp b/Benchmark.cpp
index 0770da7..e81cd61 100644
--- a/Benchmark.cpp
+++ b/Benchmark.cpp
@@ -181,7 +181,10 @@
 void Benchmark(const std::string& path,
                const android::sp<android::os::IVoldTaskListener>& listener) {
     std::lock_guard<std::mutex> lock(kBenchmarkLock);
-    android::wakelock::WakeLock wl{kWakeLock};
+    auto wl = android::wakelock::WakeLock::tryGet(kWakeLock);
+    if (!wl.has_value()) {
+        return;
+    }
 
     PerformanceBoost boost;
     android::os::PersistableBundle extras;