* Refactor OpenDingux build scripts
Created a common build.sh script that takes the target architecture as a
command line argument.
Updated existing build scripts, now they call build.sh with the matching
target.
This avoids code duplication and should help maintaining the build
script.
* Split the buildroot prepare and build steps
If the buildroot compilation fails, it will be run again the next time
the script is called. This was not the case before, as the buildroot
step was skipped when the buildroot folder existed.
* minor fixes
Gleb Mazovetskiy
Guillaume Roche