adding a scribe logger in leveldb to log leveldb deploy stats

Summary:
as subject.

A new log is written to scribe via thrift client when a new db is opened and when there is
a compaction.

a new option var scribe_log_db_stats is added.

Test Plan: manually checked using command "ptail -time 0 leveldb_deploy_stats"

Reviewers: dhruba

Differential Revision: https://reviews.facebook.net/D4659

fbcode.sh

@@ -11,6 +11,10 @@ TOOLCHAIN_LIB_BASE="/mnt/gvfs/third-party/$TOOLCHAIN_REV/gcc-4.6.2-glibc-2.13"
 # always build thrift server
 export USE_THRIFT=1
 
+if ! test "$NO_SCRIBE"; then
+export USE_SCRIBE=1
+fi
+
 # location of libhdfs libraries
 if test "$USE_HDFS"; then
   JAVA_HOME="/usr/local/jdk-6u22-64"