Don't use shell in make file
Don't use shell in make file

...when there are alternatives. (It's faster and safer.)

Signed-off-by: Zoran Jovanovic <0ee21e7adbc0df4a5a950a840013dacc99ef5b6b@sony.com>

omnirom/android_hardware_sony_timekeep,sonyxperiadev/timekeep,omnirom/android_hardware_sony_timekeep,sonyxperiadev/timekeep