ARM and uARM will conflict with build.py

[ytsuboi]

ARM and uARM shares same directory to store temporary object files for target specific APIs. Therefore, we have to clean binaries (trash "build" folder manually) before change to another target touching.

We want "trash build folder" option for build.py

[emilmont]

Hi Ytsuboi,

(1) The object files for separate toolchains are stored in separate directories, therefore you have not to worry about it. Although, yes, we did not propagate the "clean" option from the command line to the library build functions.
Now you can actually specify "-c" on the command line to rebuild from scratch a library, independently from the previously existing generated files. 76578ad

(2) This does delete the build for every target, and every toolchain: it is a quite simple action and you do not need a tool for that: the operating system command line is good enough (ie: "rm -rf build").

Cheers,
Emilio