dalvik/libdex: Change to -O2 if we're building with -O3

This is a workaround for an apparent gcc bug.
https://bugs.launchpad.net/linaro-android/+bug/948255

Signed-off-by: Bernhard Rosenkraenzer <Bernhard.Rosenkranzer@linaro.org>
dalvik/libdex: Don't reduce optimization level to -O2

Don't reduce optimization level to -O2: It's sufficient to disable
function inlining

Change-Id: Ie6d9978cf0bf0e49cfa296c09c4eba913f22c303
Signed-off-by: Bernhard Rosenkraenzer <Bernhard.Rosenkranzer@linaro.org>