adb: Don't force -O2

Don't force -O2 over -O3 -- the O2 hardcode is there to force
optimizations, not to reduce them...

Signed-off-by: Amit Pundir <amit.pundir@linaro.org>
core: Fix build in ISO C++11 mode

Fix compatibility with ISO C++11 compilers

Signed-off-by: Bernhard Rosenkraenzer <Bernhard.Rosenkranzer@linaro.org>
Change-Id: I8f9aa775b5681d4d8c5202a1a1935acb4efa4171