Add compile time option to memory management for low spec devices (Dali::Vector,...

Add compile time option to memory management for low spec devices (Dali::Vector, OrderedSet and memory pool)

Let we give some option to reduce memory capacity for low spec devices.

If app create a lots of Actors and release all of them,
the memory might not be reduced, since we don't release capacity of continous array.

Most of memory bottleneck occured at Transform::Data and Node memory pool, and
Graphics::CommandBuffer.

CommandBuffer pool control at dali-adaptor. So let we control what dali-core
can reduce capacities first.

Note : 64bit OS will always use memory pool feature even if we give compile option
, due to KeyType is uint32_t.

USAGE :

 * gbs build -A armv7l --include-all --define "%enable_low_spec_memory_management 1"

 * cmake -DCMAKE_INSTALL_PREFIX=$DESKTOP_PREFIX -DENABLE_LOW_SPEC_MEMORY_MANAGEMENT=ON

Change-Id: Ifeb2e81a5e56fd31b7a61e55dc311f1205b8dfa8
Signed-off-by: Eunki Hong <eunkiki.hong@samsung.com>