Change the defaults for shared_ptr.

By default shared_ptr is now assumed to be
in the standard <memory> header and in the
std namespace.

Previously the way the ifdefs were structured if the appropriate
variable was not defined, it would default to <t1/memory>.

The new defaults are more future proof.

Change-Id: If457806191196be2b6425b8289ea7a3488a27445
1 file changed