random: replace non-blocking pool with a Chacha20-based CRNG

The CRNG is faster, and we don't pretend to track entropy usage in the
CRNG any more.

Signed-off-by: Theodore Ts'o <tytso@mit.edu>

lib/Makefile

@@ -22,7 +22,7 @@ KCOV_INSTRUMENT_hweight.o := n
 lib-y := ctype.o string.o vsprintf.o cmdline.o \
 	 rbtree.o radix-tree.o dump_stack.o timerqueue.o\
 	 idr.o int_sqrt.o extable.o \
-	 sha1.o md5.o irq_regs.o argv_split.o \
+	 sha1.o chacha20.o md5.o irq_regs.o argv_split.o \
 	 flex_proportions.o ratelimit.o show_mem.o \
 	 is_single_threaded.o plist.o decompress.o kobject_uevent.o \
 	 earlycpio.o seq_buf.o nmi_backtrace.o nodemask.o