logd: optimize code hotspots

Discovered that we had a few libc hotspots. Adjust code to generally
reduce or nullify the number of calls to malloc, free, strlen,
strcmp, strncmp, memcmp & strncasecmp. Total gain looks to be about
3% of logd's processing time. malloc still contributes to 3%, but all
others are now total 0.5%.

Bug: 23685592
Change-Id: Ife721121667969260cdb8b055524ae90f5911278
diff --git a/logd/LogBufferElement.h b/logd/LogBufferElement.h
index 4877939..30e43c6 100644
--- a/logd/LogBufferElement.h
+++ b/logd/LogBufferElement.h
@@ -64,7 +64,7 @@
     unsigned short getDropped(void) const { return mMsg ? 0 : mDropped; }
     unsigned short setDropped(unsigned short value) {
         if (mMsg) {
-            free(mMsg);
+            delete [] mMsg;
             mMsg = NULL;
         }
         return mDropped = value;