target/arm: Wrap arm_rebuild_hflags calls with tcg_enabled

target/arm: Wrap arm_rebuild_hflags calls with tcg_enabled

This is in preparation to moving the hflags code into its own file
under the tcg/ directory.

Signed-off-by: Fabiano Rosas <farosas@suse.de>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Tested-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>