Remove duplicated _rand48 implementation. Use stdlib version instead

Originally, there are _rand48 (in libc/bionic/_rand48.c) and __rand48
(in libc/stdlib/_rand48.c) implemented in bionic.  Besides the naming,
the functionality is identical.  This patch removes the duplicated
_rand48.  Also, drand48 and erand48 are modified accordingly.

Change-Id: Ie5761a0a97f45df8538222a77edacb7c3e0125d7
5 files changed