store: fix deadlock caused by conflicting lock order

[BurtonQin]

GRAPH_POOL is locked before GRAPH_CONSOLIDATE at L102 and L103, L961 and L961

sonic/src/store/fst.rs

Lines 102 to 103 in fd7a21b

	GRAPH_POOL.read().unwrap().len(),
	GRAPH_CONSOLIDATE.read().unwrap().len(),

sonic/src/store/fst.rs

Lines 960 to 961 in fd7a21b

	GRAPH_POOL.write().unwrap(),
	GRAPH_CONSOLIDATE.write().unwrap(),

However, their lock order reverses at L200 and L203.

sonic/src/store/fst.rs

Lines 200 to 203 in fd7a21b

	let graph_consolidate_read = GRAPH_CONSOLIDATE.read().unwrap();
	for key in &*graph_consolidate_read {
	if let Some(store) = GRAPH_POOL.read().unwrap().get(&key) {

This may cause a deadlock:

Thread-A	Thread-B
A.lock()
	B.lock()
B.lock()//deadlock!
	A.lock()//deadlock!

The patch is to enforce the order for the two locks.

[valeriansaliou]

Looks good, thank you.