Upgrade to the current NetBSD rand implementation.

Also add basic unit tests.

Change-Id: I7fc7ef61d47c1e8fdf8b8eff67a635220c3afd56
diff --git a/libc/Android.mk b/libc/Android.mk
index 13d2647..2fc4300 100644
--- a/libc/Android.mk
+++ b/libc/Android.mk
@@ -140,7 +140,6 @@
 	stdio/__sprintf_chk.c \
 	stdio/__vsnprintf_chk.c \
 	stdio/__vsprintf_chk.c \
-	stdlib/_rand48.c \
 	stdlib/assert.c \
 	stdlib/atexit.c \
 	stdlib/atoi.c \
@@ -151,19 +150,14 @@
 	stdlib/div.c \
 	stdlib/exit.c \
 	stdlib/getenv.c \
-	stdlib/jrand48.c \
 	stdlib/ldiv.c \
 	stdlib/lldiv.c \
 	stdlib/locale.c \
-	stdlib/lrand48.c \
-	stdlib/mrand48.c \
-	stdlib/nrand48.c \
 	stdlib/putenv.c \
 	stdlib/qsort.c \
 	stdlib/seed48.c \
 	stdlib/setenv.c \
 	stdlib/setjmperr.c \
-	stdlib/srand48.c \
 	stdlib/strntoimax.c \
 	stdlib/strntoumax.c \
 	stdlib/strtod.c \
@@ -265,8 +259,6 @@
 	bionic/clearenv.c \
 	bionic/dirname.c \
 	bionic/dirname_r.c \
-	bionic/drand48.c \
-	bionic/erand48.c \
 	bionic/err.c \
 	bionic/fdprintf.c \
 	bionic/fork.c \
@@ -342,6 +334,14 @@
 	upstream-netbsd/libc/regex/regfree.c \
 	upstream-netbsd/libc/stdio/getdelim.c \
 	upstream-netbsd/libc/stdio/getline.c \
+	upstream-netbsd/libc/stdlib/drand48.c \
+	upstream-netbsd/libc/stdlib/erand48.c \
+	upstream-netbsd/libc/stdlib/jrand48.c \
+	upstream-netbsd/libc/stdlib/lrand48.c \
+	upstream-netbsd/libc/stdlib/mrand48.c \
+	upstream-netbsd/libc/stdlib/nrand48.c \
+	upstream-netbsd/libc/stdlib/_rand48.c \
+	upstream-netbsd/libc/stdlib/srand48.c \
 	upstream-netbsd/libc/stdlib/tdelete.c \
 	upstream-netbsd/libc/stdlib/tfind.c \
 	upstream-netbsd/libc/stdlib/tsearch.c \