Add Linker Optimizations

* Make these optional as well as the Clang optimizations.
* Enable using OPTIMIZE_LINKER=y to BoardConfig of your device.

Signed-off-by: Chet Kener <Cl3Kener@gmail.com>
Change-Id: I984f428022a68a825aa041866e8d456bd6411f79

Conflicts:
	core/combo/select.mk