BUILD: threads: Rename SPIN/RWLOCK macros using HA_ prefix

This remove any name conflicts, especially on Solaris.
diff --git a/src/buffer.c b/src/buffer.c
index db2e053..b365888 100644
--- a/src/buffer.c
+++ b/src/buffer.c
@@ -75,7 +75,7 @@
 	if (global.tune.buf_limit)
 		pool2_buffer->limit = global.tune.buf_limit;
 
-	SPIN_INIT(&buffer_wq_lock);
+	HA_SPIN_INIT(&buffer_wq_lock);
 
 	buffer = pool_refill_alloc(pool2_buffer, pool2_buffer->minavail - 1);
 	if (!buffer)