rocksdb: Fix compile error for DEBUG_BUILD

Fixed do_compile error when DEBUG_BUILD = "1":
db/write_thread.cc:183:14: error: 'state' may be used uninitialized in this function [-Werror=maybe-uninitialized]

Signed-off-by: Robert Yang <liezhi.yang@windriver.com>
Signed-off-by: Khem Raj <raj.khem@gmail.com>

meta-oe/recipes-dbs/rocksdb/files/0001-db-write_thread.cc-Initialize-state.patch

@@ -0,0 +1,31 @@
+From 49dcd22dcf1aae5995c42eac0fda68516fc1cd43 Mon Sep 17 00:00:00 2001
+From: Robert Yang <liezhi.yang@windriver.com>
+Date: Wed, 19 Jun 2019 17:57:24 +0800
+Subject: [PATCH] db/write_thread.cc: Initialize state
+
+Fixed an error when compiled without -O2:
+db/write_thread.cc:183:14: error: 'state' may be used uninitialized in this function [-Werror=maybe-uninitialized]
+
+Upstream-Status: Pending
+
+Signed-off-by: Robert Yang <liezhi.yang@windriver.com>
+---
+ db/write_thread.cc | 2 +-
+ 1 file changed, 1 insertion(+), 1 deletion(-)
+
+diff --git a/db/write_thread.cc b/db/write_thread.cc
+index 835992c..6f99a11 100644
+--- a/db/write_thread.cc
++++ b/db/write_thread.cc
+@@ -59,7 +59,7 @@ uint8_t WriteThread::BlockingAwaitState(Writer* w, uint8_t goal_mask) {
+ 
+ uint8_t WriteThread::AwaitState(Writer* w, uint8_t goal_mask,
+                                 AdaptationContext* ctx) {
+-  uint8_t state;
++  uint8_t state = 0;
+ 
+   // 1. Busy loop using "pause" for 1 micro sec
+   // 2. Else SOMETIMES busy loop using "yield" for 100 micro sec (default)
+-- 
+2.7.4
+

meta-oe/recipes-dbs/rocksdb/rocksdb_git.bb

@@ -12,6 +12,7 @@ PV = "6.5.2"
 
 SRC_URI = "git://github.com/facebook/${BPN}.git;branch=${SRCBRANCH} \
            file://0001-Fix-build-breakage-from-lock_guard-error-6161.patch \
+           file://0001-db-write_thread.cc-Initialize-state.patch \
           "
 
 S = "${WORKDIR}/git"