clean up more dead code

  - SkSHA1 is unused
  - SkRunnable is obsolete now that we have std::function

BUG=skia:
GOLD_TRYBOT_URL= https://gold.skia.org/search2?unt=true&query=source_type%3Dgm&master=false&issue=1705583003

Review URL: https://codereview.chromium.org/1705583003
diff --git a/tests/PathOpsThreadedCommon.cpp b/tests/PathOpsThreadedCommon.cpp
index c9a06f0..a1a65b7 100644
--- a/tests/PathOpsThreadedCommon.cpp
+++ b/tests/PathOpsThreadedCommon.cpp
@@ -17,6 +17,6 @@
 
 void PathOpsThreadedTestRunner::render() {
     SkTaskGroup().batch(fRunnables.count(), [&](int i) {
-        fRunnables[i]->run();
+        (*fRunnables[i])();
     });
 }