build/core: Use better default compiler flags

Use -O3 for the compiler, -O2 for the linker

Signed-off-by: Amit Pundir <amit.pundir@linaro.org>
build/core: Fix build errors

- Include task hooks only if they exists
- Fix typos

Signed-off-by: Amit Pundir <amit.pundir@linaro.org>

Conflicts:
	core/legacy_prebuilts.mk
build/core: Don't use -fno-strict-aliasing

Don't use -fno-strict-aliasing: It's no longer needed.

Signed-off-by: Amit Pundir <amit.pundir@linaro.org>
build: Don't add -fno-strict-aliasing to HOST compiler flags

Change-Id: I07eef86f11ec3761e0922855cb6ff881c2773966
Signed-off-by: Bernhard Rosenkraenzer <Bernhard.Rosenkranzer@linaro.org>
build: Explicitly disable -Werror=strict-alising for HOST builds

Change-Id: Ib1e834951196ab3ea6acbe47c27eebe5633f55d2
Signed-off-by: Bernhard Rosenkraenzer <Bernhard.Rosenkranzer@linaro.org>
build: Add option to disable strict-aliasing optimizations

This is useful for builds that pull in unmodified AOSP repositories
that can't be compiled with strict-aliasing compliance enabled

Signed-off-by: Amit Pundir <amit.pundir@linaro.org>