Fix lsan build for Fuchsia

[wiktorg]

Summary

https://reviews.llvm.org/D130237 missed ProcessThreads declaration used by Fuchsia causing build failures.

[haowei]

It is not just for Fuchsia, the previous change breaks all LSan build because the function declaration does not match the definition.

compiler-rt/lib/lsan/lsan_common.cpp

 void ForEachExtraStackRangeCb(uptr begin, uptr end, void *arg) {
   Frontier *frontier = reinterpret_cast<Frontier *>(arg);
   ScanRangeForPointers(begin, end, frontier, "FAKE STACK", kReachable);
 }
 
 #  if SANITIZER_FUCHSIA
 
 // Fuchsia handles all threads together with its own callback.
-static void ProcessThreads(SuspendedThreadsList const &, Frontier *) {}
+static void ProcessThreads(SuspendedThreadsList const &, Frontier *, tid_t,
+                           uptr) {}
 
 #  else
 
 #    if SANITIZER_ANDROID
 // FIXME: Move this out into *libcdep.cpp
 extern "C" SANITIZER_WEAK_ATTRIBUTE void __libc_iterate_dynamic_tls(
     pid_t, void (*cb)(void *, void *, uptr, void *), void *);
 #    endif