Runtime::PreZygoteFork returns void, not boolean.

This method aborts on failure (as it should) and unconditionally
returns true, so making it return void simplifies callers.

Change-Id: Iae39bd327f20311579ece47efa8afd1be7defce9
diff --git a/runtime/native/dalvik_system_ZygoteHooks.cc b/runtime/native/dalvik_system_ZygoteHooks.cc
index 2af5324..1008491 100644
--- a/runtime/native/dalvik_system_ZygoteHooks.cc
+++ b/runtime/native/dalvik_system_ZygoteHooks.cc
@@ -91,9 +91,8 @@
 static jlong ZygoteHooks_nativePreFork(JNIEnv* env, jclass) {
   Runtime* runtime = Runtime::Current();
   CHECK(runtime->IsZygote()) << "runtime instance not started with -Xzygote";
-  if (!runtime->PreZygoteFork()) {
-    LOG(FATAL) << "pre-fork heap failed";
-  }
+
+  runtime->PreZygoteFork();
 
   // Grab thread before fork potentially makes Thread::pthread_key_self_ unusable.
   Thread* self = Thread::Current();