rrpc: Round-robin sector target with cost-based gc

This target allows an Open-Channel SSD to be exposed asas a block
device.

It implements a round-robin approach for sector allocation,
together with a greedy cost-based garbage collector.

Signed-off-by: Matias Bjørling <m@bjorling.me>
Signed-off-by: Jens Axboe <axboe@fb.com>
diff --git a/drivers/lightnvm/Makefile b/drivers/lightnvm/Makefile
index e2428e0..7e0f42a 100644
--- a/drivers/lightnvm/Makefile
+++ b/drivers/lightnvm/Makefile
@@ -4,3 +4,4 @@
 
 obj-$(CONFIG_NVM)		:= core.o
 obj-$(CONFIG_NVM_GENNVM) 	+= gennvm.o
+obj-$(CONFIG_NVM_RRPC)		+= rrpc.o