libutils: RefBase DEBUG_REF love

Done here:
- path saved to a useable location on host
- path always printed (for visibility for new users)
- open(.., 666) - That's '01204' not '0644' oops

Future considerations:
- make defines constexpr instead of ifdef
- copy malloc hook design to avoid needing to recompile code
- make libutilscallstack default on host
- run libutils tests, not just test compile debug mode
- code incorrectly prints ref 'doesn't exist'
  seems it's gotten out of sync, but still good enough
  to use stacktraces

Bug: 244325464
Test: manual
Change-Id: I732e5b8aec3cd946ef3559a2a814caf693846cc0

libutils/RefBase.cpp

@@ -49,7 +49,11 @@
 
 // folder where stack traces are saved when DEBUG_REFS is enabled
 // this folder needs to exist and be writable
+#ifdef __ANDROID__
 #define DEBUG_REFS_CALLSTACK_PATH "/data/debug"
+#else
+#define DEBUG_REFS_CALLSTACK_PATH "."
+#endif
 
 // log all reference counting operations
 #define PRINT_REFS 0
@@ -324,11 +328,11 @@ public:
             char name[100];
             snprintf(name, sizeof(name), DEBUG_REFS_CALLSTACK_PATH "/%p.stack",
                      this);
-            int rc = open(name, O_RDWR | O_CREAT | O_APPEND, 644);
+            int rc = open(name, O_RDWR | O_CREAT | O_APPEND, 0644);
             if (rc >= 0) {
                 (void)write(rc, text.string(), text.length());
                 close(rc);
-                ALOGD("STACK TRACE for %p saved in %s", this, name);
+                ALOGI("STACK TRACE for %p saved in %s", this, name);
             }
             else ALOGE("FAILED TO PRINT STACK TRACE for %p in %s: %s", this,
                       name, strerror(errno));