gcc: Assume '-O2' by default for building gcc target libraries

The gcc target libraries (e.g. libstdc++) are currently built without
any optimisation flag when `CT_CC_GCC_ENABLE_TARGET_OPTSPACE` is not
enabled and default to `-O0` unless user explicitly specifies an
optimisation flag.

This commit updates the gcc build script to assume `-O2` for building
target libraries unless user provides a different optimisation flag.

Note also that this is the default behaviour for gcc when
C[XX]FLAGS_FOR_TARGET is not overridden.

Signed-off-by: Stephanos Ioannidis <root@stephanos.io>

0 files changed, 0 insertions, 0 deletions