Disable call stacks on every OS except Linux/Android

To keep libutils (and consequently libbinder) as compact
and portable as possible, this disables call stacks on all
operating systems except Linux and Android.

Bug: 224644083
Test: m
Change-Id: I0d77c49022e852c2b8607f555174c4f9d54ed3df
diff --git a/libutils/RefBase.cpp b/libutils/RefBase.cpp
index 99fefee..4ddac3d 100644
--- a/libutils/RefBase.cpp
+++ b/libutils/RefBase.cpp
@@ -50,7 +50,7 @@
 // log all reference counting operations
 #define PRINT_REFS 0
 
-#if !defined(_WIN32) && !defined(__APPLE__)
+#if defined(__linux__)
 // CallStack is only supported on linux type platforms.
 #define CALLSTACK_ENABLED 1
 #else