Update host linux toolchain to gcc 4.8

This patch ensures the build system uses the prebuilt gcc-4.8 toolchain
when building host Linux binaries, instead of the gcc-4.6 one.

Change-Id: I7b449650714ba4314a780827e0243f2af40ec82c
Signed-off-by: Chet Kener <Cl3Kener@gmail.com>
Move definition of -D__ARM_FEATURE_LPAE=1 cflag to top-level.

LPAE indicates better instructions can be used when atomicity guarantees are
needed. However, LPAE's presence isn't advertised by clang/GCC. We fake an
ARM feature to advertise its presence on architectures where it is.
Also, add a TODO documenting that cortex-a15 is not the correct CPU variant
for krait.

Change-Id: I02a1248025c32d94eca0bc8a249dc524f1ac9c36
Signed-off-by: Chet Kener <Cl3Kener@gmail.com>
USE_O3_OPTIMIZATION Flag

This commit will give you the option to use some of my -O3 optimizations with some warning disabling flags and just a few others not included in -O3 that I think are nice.

To use place USE_O3_OPTIMIZATIONS := true or even simply USE_O3_OPTIMIZATIONS=true in your device's BoardConfig.mk.

I did not include -O3 on TARGET_thumb_CFLAGS because that is usually the reason the build will fail on some devices and really just adds lots of bloat without a noticeable difference. You can always change that flag to -O3 if you desire.

This commit also will bump your host toolchain version from 4.6 to 4.8 (which is already included in the manifest for 5.0.1) Since Host 4.8 is already here we may as well use it.

Any questions please refer them to me on hangouts.

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