db/write_thread.cc: Initialize state (#6275)

Summary:
Fixed an error when compiled with -Og:
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>
Pull Request resolved: https://github.com/facebook/rocksdb/pull/6275

Differential Revision: D19381755

fbshipit-source-id: a90bf3cd4a7248d9d71219e918fc6253deb97e3c

db/write_thread.cc

@@ -61,7 +61,7 @@ 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)