Implement rand/srand in terms of random/srandom.

Code developed for glibc or older versions of bionic might expect more
randomness than the BSD implementation provides.

Bug: 15829381
Change-Id: Ia5a908a816e0a5f0639f514107a6384a51ec157e
diff --git a/libc/Android.mk b/libc/Android.mk
index 765f4d2..5d6c2e0 100644
--- a/libc/Android.mk
+++ b/libc/Android.mk
@@ -178,6 +178,7 @@
     bionic/pthread_sigmask.cpp \
     bionic/ptrace.cpp \
     bionic/raise.cpp \
+    bionic/rand.cpp \
     bionic/readlink.cpp \
     bionic/reboot.cpp \
     bionic/recv.cpp \
@@ -295,7 +296,6 @@
     upstream-netbsd/lib/libc/stdlib/mrand48.c \
     upstream-netbsd/lib/libc/stdlib/nrand48.c \
     upstream-netbsd/lib/libc/stdlib/_rand48.c \
-    upstream-netbsd/lib/libc/stdlib/rand.c \
     upstream-netbsd/lib/libc/stdlib/rand_r.c \
     upstream-netbsd/lib/libc/stdlib/seed48.c \
     upstream-netbsd/lib/libc/stdlib/srand48.c \