[sanitizer] Restrict querying VM size on Darwin only to iOS devices

[kubamracek]

Summary

We currently do this for SANITIZER_IOS, which includes devices *and* simulators. This change opts out the check for simulators to unify the behavior with macOS, because VM size is really a property of the host OS, and not the simulator.

compiler-rt/lib/sanitizer_common/sanitizer_mac.cpp

   LeakyResetEnv(kDyldInsertLibraries, new_env);
 }
 #endif  // SANITIZER_GO
 
 char **GetArgv() {
   return *_NSGetArgv();
 }
 
-#if SANITIZER_IOS
+#if SANITIZER_IOS && !SANITIZER_IOSSIM
 // The task_vm_info struct is normally provided by the macOS SDK, but we need
 // fields only available in 10.12+. Declare the struct manually to be able to
 // build against older SDKs.
 struct __sanitizer_task_vm_info {
   mach_vm_size_t virtual_size;
   integer_t region_count;
   integer_t page_size;
   mach_vm_size_t resident_size;