libbinder: separate OS-specific code from Utils.cpp

Separate the OS-specific functions setNonBlocking and
getRandomBytes from Utils.cpp into a separate OS-specific
OS.cpp file that other operating systems can override at
build time.

Bug: 224644083
Test: build Trusty
Change-Id: I2703fb81d4370b5f6264556ae57fdddb0573971a
diff --git a/libs/binder/Utils.h b/libs/binder/Utils.h
index 37c1262..7c6d6f1 100644
--- a/libs/binder/Utils.h
+++ b/libs/binder/Utils.h
@@ -15,11 +15,10 @@
  */
 
 #include <stddef.h>
+#include <sys/uio.h>
 #include <cstdint>
 #include <optional>
 
-#include <android-base/result.h>
-#include <android-base/unique_fd.h>
 #include <log/log.h>
 #include <utils/Errors.h>
 
@@ -36,10 +35,6 @@
 // avoid optimizations
 void zeroMemory(uint8_t* data, size_t size);
 
-android::base::Result<void> setNonBlocking(android::base::borrowed_fd fd);
-
-status_t getRandomBytes(uint8_t* data, size_t size);
-
 // View of contiguous sequence. Similar to std::span.
 template <typename T>
 struct Span {