libutils: include what you use

These includes are included transitively by liblog, but not by the VNDK
version of liblog.

Bug: 33241851
Test: links with BOARD_VNDK_VERSION := current
Change-Id: Ide4aee3cacad2a2bf6bd0cbdf0254c6c245f4020

libutils/ProcessCallStack.cpp

@@ -20,6 +20,8 @@
 #include <utils/ProcessCallStack.h>
 
 #include <dirent.h>
+#include <unistd.h>
+
 #include <memory>
 
 #include <utils/Printer.h>

libutils/misc.cpp

@@ -16,15 +16,11 @@
 
 #define LOG_TAG "misc"
 
-//
-// Miscellaneous utility functions.
-//
 #include <utils/misc.h>
+
+#include <pthread.h>
+
 #include <utils/Log.h>
-
-#if !defined(_WIN32)
-#endif
-
 #include <utils/Vector.h>
 
 using namespace android;