liblog: introduce ANDROID_LOG_* flags

Move away from using POSIX open(2) flags and introduce ANDROID_LOG_* flags to
replace them. Add security by preventing random mode flags from getting into
underlying POSIX calls. ANDROID_LOG_* flags overlap POSIX O_* flag definitions.

Change-Id: Ib32bb64c287e8bf150be62242e1ba46bb37839fc
diff --git a/debuggerd/tombstone.cpp b/debuggerd/tombstone.cpp
index 4233d46..e927ea3 100644
--- a/debuggerd/tombstone.cpp
+++ b/debuggerd/tombstone.cpp
@@ -453,7 +453,7 @@
   }
 
   logger_list = android_logger_list_open(
-      android_name_to_log_id(filename), O_RDONLY | O_NONBLOCK, tail, pid);
+      android_name_to_log_id(filename), ANDROID_LOG_RDONLY | ANDROID_LOG_NONBLOCK, tail, pid);
 
   if (!logger_list) {
     ALOGE("Unable to open %s: %s\n", filename, strerror(errno));