Fixing a bunch of alloy clang issues.

src/poly/threading.h

@@ -18,6 +18,9 @@
 namespace poly {
 namespace threading {
 
+// Gets the current high-perforance tick count.
+uint64_t ticks();
+
 // Gets a stable thread-specific ID, but may not be. Use for informative
 // purposes only.
 uint32_t current_thread_id();