liblog: remove memset() before recv().

This is unneeded, since we're already checking the length returned by
recv() and log_msg that is read for validity.

It costs ~4% of CPU with `logcat -s` and ~2% of CPU when running
simpleperf for 1 second on walleye on master.

Bug: 144311420
Test: logcat works, simpleperf doesn't show memset() costing as much.
Change-Id: I986e7e96518774034340f1b1201a2071a904e3bb
diff --git a/liblog/logd_reader.cpp b/liblog/logd_reader.cpp
index 4e2dc66..d7b893d 100644
--- a/liblog/logd_reader.cpp
+++ b/liblog/logd_reader.cpp
@@ -392,8 +392,6 @@
     return ret;
   }
 
-  memset(log_msg, 0, sizeof(*log_msg));
-
   /* NOTE: SOCK_SEQPACKET guarantees we read exactly one full entry */
   ret = TEMP_FAILURE_RETRY(recv(ret, log_msg, LOGGER_ENTRY_MAX_LEN, 0));
   if ((logger_list->mode & ANDROID_LOG_NONBLOCK) && ret == 0) {