In our previous FORTIFY_SOURCE change, we started using a custom
inline for memcpy(), rather than using GCC's __builtin_memcpy_chk().
This allowed us to delete our copy of __memcpy_chk(), and replace it
by __memcpy_chk2().
Apparently GCC uses __memcpy_chk() outside of __builtin_memcpy_chk().
Specifically, __memcpy_chk() is used by __builtin__memMOVE_chk() under
certain optimization levels.
Keep the old __memcpy_chk() function around, and have it call into
__memcpy_chk2().
Change-Id: I2453930b24b8a492a3b6ed860e18d92a6b762b80
b2060b027c